I have a lot of questions. My former boyfriend lived in sin for four years. I was not saved yet, but he was. He called it off because he could no longer live in sin, and he has to get right in his heart and mind and with God. I am here 100% for him because I love him. He moved out and is seeking answers from God. I fully understand why he needs to, as well as why we need to build our foundation through God. I know you can't tell the future by any means, but if he finds what he is searching for, as well as forgiveness, can we make this work? I have been reading the Bible every day and have given my life to God. How can I help him through this terrible time? How do I grow as a Christian?
I try to pay attention to what people don't say when they write, whether it is intentional or accidental, because the critical elements left out often point to the source of the problems. What jumped out at me in your note is your mention that your boyfriend lived in sin for four years, but you did not include yourself as a participant in sin. At first I considered it accidental, but all the way through I found no hint that you considered the fornication you committed to be wrong, and that troubling. In fact everything is about his problems. You want to help him, but I keep wondering: What about you?
If you desire to grow as a Christian, then you need to recognize the problem of sin.
"For you, brethren, have been called to liberty; only do not use liberty as an opportunity for the flesh, but through love serve one another. For all the law is fulfilled in one word, even in this: "You shall love your neighbor as yourself." But if you bite and devour one another, beware lest you be consumed by one another! I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh. For the flesh lusts against the Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish. But if you are led by the Spirit, you are not under the law. Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God. But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, self-control. Against such there is no law. And those who are Christ's have crucified the flesh with its passions and desires. If we live in the Spirit, let us also walk in the Spirit" (Galatians 5:13-25).
I can't answer what he might decide. Clearly he concluded that he could not live righteous while being your boyfriend and that should be a disturbing thought. Friends, and especially spouses, should be people make you a better person. Love "does not rejoice in unrighteousness, but rejoices with the truth" (I Corinthians 13:6). I suspect fixing this issue will go a long ways to repairing the separation.