How do I talk to my boyfriend about this issue?

I have been putting this off a bit ,but anyways. My boyfriend and I are very happy with each-other, but we do have our hickups. I hate getting mad at him, but resort to feeling so empty and upset,instead. When he ask whats wrong, i tell him nothing,because I don’t know what about the issue is whats bothering me. I get upset kinda like a reflects, or a automatic thing when ever he starts talking about other girls he has been with, or when plays his games and checks out the characters (Borderlands 2-Mad Moxxi) He says the name of his most previous ex girlfriend everyday. some time because he’s talking bout her, or he calls me her name on accident. her name is similar to mine, and he said that’s why he does it. He gets all upset when ever he feels I’m upset, I don’t want to make him get a panic attack or anxiety attack, As well as I hate being in a bad or upset state in my relationships. So I just tell him everything is fine and act happy. He also post these fan art pictures of characters on facebook which have big boobs and everything. I’m very small chested and get upset and get low self esteem. Either I need to stop being so sensitive and just ignore it, or he needs to watch his words. I don’t know why I get so upset automatically at the mention of another girl before me. Can anyone give me advice on this issue. If you’d like to help me more in-depth, you may “funmail” me. and we can go from there, thank you <3