To start off, I was baptized at the church of Christ I attended. Before that time I was getting really bad into drugs, and my drinking was off the charts. I don't remember what I knew of Christ, just that I needed to be baptized to enter Heaven.
I managed to give up drugs for a year. Mom was diagnosed with stage 4 breast cancer and was in the hospital for the last time, and those old habits started sneaking back in. Mom passed about a month later, and I managed to give up the drugs for good that time. But the drinking, not so much.
About a year after mom passed I got married to a girl I had been having an on and off relationship with for several years. She got pregnant, and we rushed into the marriage. We were married for a few years and are currently separated. The reason she gave me for wanting a divorce was she wasn't happy. And I understand why. I let my drinking get in the way and I wasn't giving her the attention she needed. Just a few days after she told me she wasn't happy and wanted a divorce, she went out with another guy she had known for years, and I found out they slept together. I wasn't ready to give up on my marriage until then. But I'm having my doubts.
Is it still considered adultery if she conveyed she wanted a divorce? If I marry again later, am I committing sin?
I've been thinking a lot the past few weeks on whether or not I truly believed when I was baptized, or just acting out of pure emotion. I know a great deal more now than I did at the time of my baptism, and that just causes more doubt. All of these things run through my mind on a daily basis, and I don't know what to do. I've prayed, talked to God in my mind over and over, but I still feel confused.
I'm sorry to hear of all the difficulties you've faced in your life.
You and your wife are not divorced. Your wife has expressed an intention of divorcing you, but she has not carried it out. She decided, instead, to commit adultery with another man. Even if she had waited until after the divorce was completed, her acts of sex with another man would still be counted as adultery because she remains bound by her covenant with you.
You, however, are allowed to divorce her because of her adultery and you would be allowed to marry someone else. "And I say to you, whoever divorces his wife, except for immorality, and marries another woman commits adultery" (Matthew 19:9). Just don't make the same mistake your wife made. Wait until your divorce is final and marry another woman before having sex. In fact, I would recommend not even thinking about dating anyone until after you are free to remarry. You never know, your wife may realize her sinful condition and want to reconcile with you.
Meanwhile, the greatest thing that you can do for your own spiritual (and physical) health is to give up drinking -- not partly, but completely. I have some material that I want you to start learning:
It is common for Christians pulled back down into the mire of sin to wonder if they really were saved. I would hope that you do know much more now than when you became a Christian and I hope that years from now, you know even far more. No one is expected to know everything before they become a Christian. Please look at: Should I get baptized again?