He wants to bring her around family!?

My boyfriend and I had been together for almost three years when we broke up a few months ago. A couple months after the breakup, while we were still living together, he brought one of the women he was seeing over to meet his family and me (god knows why i was included). Shortly after this terrible event, he decides he's talking her on what was supposed to be our anniversary trip. We are now back together and i am due to move back in shortly before the new year. He wants to stay friends with this woman (who he claims he hasn't fucked since the trip), which would be fine, except for one thing; he wants to start bringing her to family events. I am extremely hurt by this, as I'm sure a good deal of his family has figured out that she was one of the other women. He thinks its the perfect setting. I wish it wasn't so important to him, probably because he hasn't even reintroduced me as his woman yet. Thoughts, advice? I need a lot of help with this one.