I Am Having a Bad Day

I'm not just having a bad day, it's going to be a bad weekend too! My boyfriend decided to arrange for us and his family to go to London for the weekend to see the rest of their family, and to take pictures at Windsor castle because my boyfriend's dad used to guard there. Sounded really good and I was looking forward to it until my bf's ex wife was invited along by my bf's dad! Great! We even all went for a meal together last night to start the weekend off, and the ex was just sat there looking miserable, which I'm sure she does to get sympathy! So now we're all in a van together going to London, and I'm going to have to see this awful woman all weekend, when she has previously threatened me and clearly hates me because I'm with her ex. Has anyone else been in this situation and can give me advice please? I like my boyfriend's family and I get on with them, but it's difficult when she's around because she seems to make them feel uncomfortable talking to me. Plus, both her and my bf love giving attention to their nephew (who is also coming on this trip), so she ends up talking to my bf more than I do. I suffer with anxiety anyway, so I'm really hating this.