Trying to move on from his previous actions

My boyfriend (23 yrs old)) is a recovering alcoholic. For months he lied to me (23yrs old) about big and small things, and never came clean about anything until I found out and confronted him about it. I broke up with him bc of the lack of trust I had in him, and after he went to rehab he asked me to give him another chance. I’ve been seeing him for a few weeks and his actions have genuinely been so much more promising. He’s being the man I needed. But I can’t stop thinking about the lying and hurtful things he did to me before. He would lust over girls online and I find myself feeling sick even seeing those celebrities online. He hid stuff and tried to lie about it, but I always found out. Now it’s so hard for me to move on, or believe that he’s not hiding anything. He keeps telling me to separate the man he was while drinking and the man he is now, bc the other guy is gone. But it’s so hard to separate them. If he did that while drinking, does he normally want to do that stuff, he just doesn’t have an excuse to now? He told me he’s disgusted by the stuff he used to do while we were together. But he knew how wrong it was before, and he hid it all so well, so he must not have felt that bad about it, right? Idk. I’m feeling so much resentment towards him. He was not great to me before, and now with all my frustration, I feel like I’m being a bad partner now. I hold a grudge for a while and that’s a major flaw of mine, but I’m not sure what to do to help. The man he was while drinking, IS him. He’s just acting different now. It’s so hard to trust him and I’m feeling so conflicted. I saw some other posts about how different partners can act while drinking and during sobriety. Any insight or encouragement is very welcome!