Screwed up situtation - bf's ex wife!

My partner and I have been together for over 3 years, he has been split up from his wife for 4 years (mutual decision) and has 2 children with her (both adults). It is his daughter's 21st next year and she has invitied friends/family to celebrate with her in Las Vegas for a few days. I get on with his daughter just fine, but his ex wife is bitter and twisted and is very jealous of our relationship, as they were always falling out when they were together and splitting up. And she will be going to Las Vegas!! My partner says it doesn't bother him that she will be there, as he is very open with everyone about our relationship and how much we love each other, but I will feel very uncomfortable and feel it's quite a screwed up situation! Part of me wants to go and show i'm the bigger person, but at the same time I will feel very awkward staying in the same hotel and having to be around her! Anyone's opinions appreciated!! xx

Thankyou

Thanks for your response, appreciated! I spoke to his daughter at weekend and she wants us all to go and all stay in the same hotel! Her attitude is "oh mum will be fine don't worry!" We went to a party not long ago where she was there in the same pub, and until she's had a drink she's fine, she said a civil 'hello' and got on with her night! Then she got absolutely wrecked and came over to me and my partner and started telling him how 'lucky he is to have me' etc.. being all mushy! Then she started going on saying 'god our relationship was crap wasn ... and 'don't forget how much money you still owe me..' blah blah and so on! She is alot to handle after a few to drink! That's what i'm concerned about! xx