The only thing I can do is tell you some of my story and the many regrets that I have from it, because I see so many examples in your posts that are parallel versions of my own past. I spent years being absolutely miserable and depressed because I let someone treat me as your boyfriend is treating you – intentionally or otherwise.
You’re second best right now with someone who is healing from a previous break-up. The first two years of a relationship I was in were dominated with, “My ex this,” “My ex that,” etc. Comparisons. And to some extent, it’s expected after four turbulent years together. But after 5 months of dating, this stuff really needs to start taking a backseat. You need to start enforcing boundaries with him and letting him know that it’s not okay. If he said something to me about “I’m glad you don’t like x (ostensibly because his ex DID),” you respond with, “Yes, I do like it. I was hoping I could get one one day.” What, is he going to dodge everything that reminds him of her?
My honest feeling is that this is too soon for him. The guy I was dating when I went through something similar was TWO YEARS out of a one-year relationship, and I let that go on for more than a year into our relationship. Even when it was over, it was poison. It’s very undermining if someone so ‘toxic’ is still involved in your present life. It would make me seriously question what your boyfriend has told you about her. And it would seriously make me wonder if that’s not just his excuse to you so he can continue chatting with her.
I am generally in the camp of, “It’s a bad idea to keep chatting with exes.” At the very least, your boyfriend needs some true no-contact time until he is confident that he no longer has feelings for her. And if she can’t respect his boundaries, or if she’s going to bother him, then he just won’t be able to have contact with her no matter how he feels about her. But is that a sacrifice he’s willing to make?
Don’t put yourself through the Hell that I allowed myself to live through. In my experience, it only got worse with time. His ex isn’t the problem – he is, and he’s going to continue allowing it to happen until you put your foot down. You have to decide if you want this to be your future. If you stay, and do not speak up, this could well be your life in 5, 10 or more years.
There is time to save this. But he’s got to stop making comparisons between the two of you. His relationship with her is over, and odds are there will be some similarities between you…that doesn’t mean they’re even worth mentioning. You are his girlfriend – not a therapist to help him heal from his ex.