I have been depressed for a while

I'm not sure when it started, probably when I was young. It got a lot worse when I was in my previous relationship as my ex was emotionally abusive and would gaslight me all the time, then not talk to me for a few days. I don't know why I stayed in the relationship, but he eventually broke it off. We continued to hang out and fool around until I found out he had a new girlfriend. About three months after, I got into a new relationship. It was probably way too soon as I still was not healed, and I'm still not even though it's been 2.5 years since my new relationship started. I'm constantly relating things from my past relationship to my new one. I'm always comparing my ex to my boyfriend. I trust him, but there has always been some doubt. I recently found out he lied to me about smoking marijuana and lied about a promise he made to me. It's not so much about the marijuana itself, but that it reminds me so much of my ex. He would lie to me about everything and smoked all then time. Now, I'm afraid that my boyfriend is doing the same and as been lying to me about everything. I can't stop feeling this way and I end up feeling like I'm the crazy girlfriend who is possessive and controlling, thinking he would be better off without me and he is only with me because he pitied me and would feel bad or is afraid I would hurt myself. I hate feeling this way, but it won't go away.