New relationship

Hey Im new to the site. My name is Laura and Im 21I am experiencing some problems in my new relationship. We have been together for about 3 months now but have known him for 5 months. I like this guy a lot, Im so comfortable around him and he is everything I want in a man, however he has a huge sense of humour which I love about him but at times it can go over the top which can make me cringe at times. Many occasions he would talk about how beautiful his exs are or how his sex past is amazing but in a joking way. At first I didnt think nothing of it because to know a person you have to be interested in their past. But I thought we had been there and talked about it. Im finding it harder to bite my lip whenever he mentions it now. I admit I am insecure about myself. My self esteem was rock bottom but over the years it has improved. I dont really need to be hearing this all the time. I mean what use is it to me to know how his exs are beautiful. I think its really unfair to bring it up when I dont put him in a similar situation talking about any of my exs not that I have had many compared to him. Do you think Im being to dramatic about this? As I though talking about your exs was a turn off hence the fact I dont brag on about my exs?