Do. Not. Go.
As much as your son wants you to go, as others have said, you'd be giving him some very messed up ideas on how relationships work, and there are waaaasay too many chances of something happening and causing unforeseen problems.
I would explain that you'd like to go to spend time with him, but you're not in a place where that is a healthy decision to make and for the sake of your mental health and continued healthy relationships all around it's best for you not to join. It will hurt both of you emotionally, but it's probably the best long term choice. If necessary, you can throw in a 'next time ~~gadget~~ son' in there to show this isn't how it always will be.
Lmao, you've never heard of Lennybot.
Scammers are stupider than you could ever imagine.