Should I go to ‘friends’ childs party?

A ‘friend’ who isn’t really much of a friend anymore has invited me and my son to her child’s party after not have spoken to each other for almost a year. We’ve had issues in the past where’s she’s not been a very nice person and just falls out with just about everyone including our big group of friends where over the years has managed to fall out with every single person for different reasons, she has fallen out with other friends of hers as well and doesn’t have really have anyone else in her life apart from family. She has always been one of those people who has to compare her child and think there the best whilst making others feel rubbish for theirs not meeting milestones as quickly for that reason I naturally distanced myself as she was making me feel rubbish most of the time. Since my child’s party last year where she acted very off with me and my family we haven’t really spoke, almost a year down the line she has now invited me to her child’s birthday and is acting all nice (I know this is to increase numbers as she doesn’t really have many people to invite) I have already politely declined her invitation however she is has messaged me since asking me again saying it would nice to see you. I know full well if I go to this party it would be to increase numbers and she probably won’t speak to me & it will feel very awkward on my part. How do I go about this situation? And do you think I am being horrible not going to a child’s party I just don’t know what to do as last thing I want to be is cruel and make anyone feel bad.