I totally get how it could make you sick to the stomach having to deal with other woman at a family event. It would make me want to puke.
On the positive side she will be the one that gets to deal with J then and hopefully he will leave you alone.
I know when my exH attends any of the kids events (the very few he does) - he glues himself to me, trying to be my friend and be helpful and its honestly getting super annoying. He is so strange sometimes I wish his girlfriend was there to deal with him.
Ask your landlord if it would be easier for him if you hired a handyman to do the small repairs and then he could reimburse you. I think that would motivate him.
Stay positive and strong. look how far you have come.
---- M 39 H 35 D5,D4 M 4 T 9 ILYBNILWY 5/18/11 Left 7/11/11 Divorced 12/1/13