my girlfriend cheated on me with my brother last year and my family wants me to be nice to them.

This all started last year I (Female 25) had a Girlfriend Garnet (Female 29) and it was a great relationship no fights, we had heaps of fun and I thought nothing was wrong with it but unfortunately I found my Girlfriend having sex with my brother Rugby (Male27) it was devastating and heart breaking seeing the two people I adored stab me in the back, so I ran and stayed with a friend until I got myself a permanent place over the next few months I kept my distance but my parents every now and then would tell me how rugby and garnet got together and how garnet is pregnant I didn't comment on it cause I just grew hate for them slowly over time.

Anyway fastfoward to last week I was invited to a family gathering and so was garnet, rugby and their daughter sapphire I tried to stay away from them because I was still hurt just seeing them, but my aunt and brother came over and said "hello" which I just nodded and walked away "my God stop being rude and say hello to your brother" I turned around and said "I have no brother, he died when he thought it was a good idea to stab me in the back!" The family and I had an argument saying I should be happy that a miracle was made and so I left so they could enjoy there miracle and be a "perfect family"

They've been texting me ever since saying how I'm selfish and how I should stop so the family can be happy..... I just need to know should I just try to bottle my hatred for garnet and rugby so the peace can be kept or cut contact?