talking about exs

My OH keeps mentioning his ex. It started off when we started watching walking dead, he made a comment about how him and his ex always watched and she was so obsessed then it started getting into little comments about how they used to go on long walks (he won't even walk the dog too far with me!) to how they done this and that. They've been broke up 2 years, he never mentions any other of his exs at all but tonight we went for a meal and he started a new job and didn't realise for a few weeks he knew someone else who worked their they'd a mutual friend THIS SAME EX. I'm fed up listening to it all the time, he also said i am different than his exs as they look like models and skinny. I'm not ugly but I am cuddly. I also found out this same ex slept with his cousin while with him and he went crazy when his friend mentioned it in front of me and asked him to leave. He also has a son from a girl he doesn't know and made a comment like "at least the sex wasn't boring when he was conceived" I don't feel like these things should be said. I also seen messages where he was texting other girls saying that I was boring in bed when we first got together (I'm self conscious and it took me a while to become comfortable with him) I don't know how to feel about all this