My boyfriend is doing nicotine and he didn’t tell me?

My boyfriend and I have been together for 3 years. We have a rocky relationship. I have trust issues and I feel triggered by things he says like “What mamma don’t know won’t kill her.” He’ll say that and says it’s from a movie and to relax. I’ve given him a hard time about trusting him and it’s driven him crazy. But he is socially awkward and stuff has come off as weird. He has a weed habit too

Overall, we’re always on the brink of breaking up because he says I don’t trust him and that he can’t forget that I’ve seen him as a piece of shit… Well, recently I found out that he’s been taking nicotine for a few months. I found a wrapper in the garbage and when I asked him, he said he started taking nicotine because of the stress in our relationship and stress at work and stress with his mom and siblings. He said he didn’t want to tell me because of how id react and he didn’t want another argument and that I always criticize him and his health habits. I don't know what to do or think but I feel hurt he didn’t tell me. I don't know if I can trust him. I don't know if I’m overreacting. Is this a red flag? What do you think?

Updates
7 mo
He says he didn’t trust in telling me because all I talk about it cheating, so he doesn’t trust me. And that he didn’t trust for me to not over react and start another argument… This is what he also said when I asked why he didn’t tell me about the nicotine
My boyfriend is doing nicotine and he didn’t tell me?
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