So my boyfriend and I have been dating for 4 months now and we have both made it clear we love each other. Even so, I feel I have been haunted by his ex girlfriend for months. She was his first love and she left him because she didn't want to deal with his internal problems. She was very unstable and he wouldn't even kiss her because of that. But it hurt him so bad when she left. 

I get very insecure when he brings her up, which he does fairly often because she is apart of many fond memories of his. I compare myself to her constantly. This he knows, and he has told me over and over that she means nothing to him now and I am so much better. I am better to him. I now know all of his internal problems and I have been kind, helpful, and respectful of them. Although he doesn't want me to see him when he's in a state because he doesn't want to lose me.

Now here's the thing. I am always scared that she is meant for him. Because I know that love can be there even when people are dysfunctional, and mess up. I have no idea if she ever had or has feeling for him truly. But I keep envisioning them together instead of he and I together. This has been a more recent development, but I don't know what this means. I love him so much and want to be with him as long as I can, but I'm worried I don't deserve him.