Thanksgiving without Mom

This is the second Thanksgiving without my mother and I am not looking forward to it. My Dad decided he wanted to be with his girlfriend on a cruise more than his own children. I was invited to my brother's house to have Thanksgiving with him and his wife, but they decided to have their dinner on Wednesday rather than Thursday because the next day they are having dinner with his wife's family. So it looks like I will be alone for Thanksgiving. Unless I decide to go to my ex husband's house and have dinner with his wife and our son. I don't know if I would feel comfortable doing this, although my son wants me to be there. My ex and I don't get along well and I don't want something to spoil Thanksgiving for our son. It sounds like he feels sorry for me because the said "No one should spend Thanksgiving alone".

Should I put my fears aside and have Thanksgiving Day dinner with my ex and his wife for my son's sake? I really don't know what to do.

Thanks!