Boyfriends ex turns up after 3 years

Long story short, my boyfriend and his ex broke up in 2016 after her getting close with a guy off tinder (who, surprise surprise, she was seeing behind his back). They stopped speaking in 2017 (and not on good terms) a few months after me and my boyfriend got together (she had been scrounging off him, messaging him random things at 3am when she would break up with her boyfriends and the final straw was payments coming out of his bank to a Netflix account in her name which she refused to look into). During this period she was extremely weird, for example. would ring up my boyfriends friends asking them to be her maid of honour when they hadn’t spoken in two years and etc.

Flash forward to now, her and her new boyfriend randomly come back to our hometown (she moved away) and go to my boyfriends gig on her birthday. She apparently asked around and tried to speak to him but he wasn’t there then, then after didn’t bother coming over when i was with him and then left shortly after my boyfriend did.

I know it might not seem that weird to some, but this girl has fallen out with everyone at this gig. She scrounged money off my boyfriends inheritance from his deceased father, physically and emotionally abused him which most people there knew about. He has removed her off everything so they are not in contact, to know about his bands gig she would have had to have looked him up. She’s also removed the majority of their mutual friends who were at that gig off all social media’s after they broke up, as she tends to not have her own friend group but only her boyfriends.

Her being there gave me major anxiety afterwards and even though it’s been a day I’m still freaked out by it. Reason I’m making this post is genuinely because I’m completely confused as to why she turned up to that gig wanting to talk to him after years of not speaking, and also mostly just to get other people’s opinion on why. 😊 (it’s also very late here so sorry for any mistakes!!)x