Your words of wisdom have been very healing. Thank you.
I wanted to give some more contextual information with regards to this ex-boyfriend.
I met him at my church. I was in a program called Beyond Divorce, and he was my small group leader as well as the organizer of this entire program. In my small group, I gave the details about what happened in my marriage. Infertility was the crises (my husband's) and while I wanted to stay in the marriage and get counseling, he would not. He stopped being sexual with me and made me sleep in a separate room for almost one year. I came home to his filling out divorce papers online. It was horrible. So I was turning to church to get right with God again and heal, and fell into a sinful error with the leader who I feel preyed on my vulnerabilities. He used to tell me, "God knows I feel betrothed to you! We can be sexual!" and I fell in. It was later that he confessed to using porn, and after I got out of the relationship I learned that his ex-wife was beaten up by him.
I told the church that I hoped he would not date participants again. He is still the leader of this group.
It is in wounded times and vulnerable times that I have been harmed with my own sexuality. I need to restore myself with the Lord and stop my sinning. Your emails are helping me, so thank you.
Your letter raises several significant issues and there is one in particular that I would like you to think about. There are warnings in the Scriptures about men like your ex-boyfriend. "But know this, that in the last days perilous times will come: For men will be lovers of themselves, lovers of money, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy, unloving, unforgiving, slanderers, without self-control, brutal, despisers of good, traitors, headstrong, haughty, lovers of pleasure rather than lovers of God, having a form of godliness but denying its power. And from such people turn away! For of this sort are those who creep into households and make captives of gullible women loaded down with sins, led away by various lusts, always learning and never able to come to the knowledge of the truth" (2 Timothy 3:1-7). Please don't misunderstand me; I'm not saying that you are normally "gullible" (or "weak-willed" as another translation renders this verse). However, as you noted because of your recent divorce, you were vulnerable, quite likely because you were going through a phase of wondering whether you caused your marriage to fall apart. The year-long lack of sexual attention from your husband didn't help matters (see I Corinthians 7:1-9).
My concern is that you are describing a church filled with false teachers. "But there were also false prophets among the people, even as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Lord who bought them, and bring on themselves swift destruction. And many will follow their destructive ways, because of whom the way of truth will be blasphemed. By covetousness they will exploit you with deceptive words; for a long time their judgment has not been idle, and their destruction does not slumber. ... and especially those who walk according to the flesh in the lust of uncleanness and despise authority. They are presumptuous, self-willed. They are not afraid to speak evil of dignitaries, whereas angels, who are greater in power and might, do not bring a reviling accusation against them before the Lord. But these, like natural brute beasts made to be caught and destroyed, speak evil of the things they do not understand, and will utterly perish in their own corruption, and will receive the wages of unrighteousness, as those who count it pleasure to carouse in the daytime. They are spots and blemishes, carousing in their own deceptions while they feast with you, having eyes full of adultery and that cannot cease from sin, enticing unstable souls. They have a heart trained in covetous practices, and are accursed children. For when they speak great swelling words of emptiness, they allure through the lusts of the flesh, through lewdness, the ones who have actually escaped from those who live in error. While they promise them liberty, they themselves are slaves of corruption; for by whom a person is overcome, by him also he is brought into bondage" (II Peter 2:1-3, 10-14, 18-19). The entire chapter of II Peter 2 is applicable, but I picked out passages that particularly address your situation. You were not married to this man, yet he claimed that because he "felt like" he was engaged to you that you had the right to a sexual relationship. The flaw is that engaged couples are not allowed to have sex; let alone people who just feel like they are engaged. Sex is reserved for husbands and wives in a marriage covenant. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). What he convinced you to do is fornication (sex outside of marriage). See "Why Sex Outside of Marriage is Wrong" for further details.
Even more disturbing is that you warned the church where you are attending and they did nothing about it! They have a man engaging in fornication, pornography, and is a sexual predator; yet, they allow the man to continue to teach a class where people are are particularly vulnerable to predators. The proper response should have been to show the man the door. "I wrote to you in my epistle not to keep company with sexually immoral people. Yet I certainly did not mean with the sexually immoral people of this world, or with the covetous, or extortioners, or idolaters, since then you would need to go out of the world. But now I have written to you not to keep company with anyone named a brother, who is sexually immoral, or covetous, or an idolater, or a reviler, or a drunkard, or an extortioner -- not even to eat with such a person" (I Corinthians 5:9-11). A person cannot engage in sex outside of marriage and expect to go to heaven, nor should they expect to be accepted as members of the church. "Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God" (I Corinthians 6:9-10). This is not to say that those who have committed these sins cannot be save, but by becoming a Christian, those sins were to be left behind. "And such were some of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God" (I Corinthians 6:11).
I strongly urge you to leave this place and find a church with morally upright people and a will to follow the New Testament teachings. If you need help finding such a church, let me know the city where you live and I'll try to find the nearest congregation where I believe you will find faithful followers of God and not followers of the flesh.