Mrs. H, I hate to say it, but your lawyer is correct...you have to find a way to deal w/your JA. Choose your battles to take to the lawyer and learn to come here to bounce things off of us. Your lawyer is there to offer legal guidance and to ensure that your monetary rights and custodial rights are taken care of. It sounds like he's getting a bit tired of you phoning him every time JA does something that's not exactly in line with the agreement.
Right now, JA is acting out because he's madder than an old wet hen over what the agreement is. He's rebelling and you are caught in the middle. Look at how he's constantly bringing up about what he makes, pays you, the house and what he's lost. State your case w/him and do not go into anything else w/him. The man loves to push your buttons. He baits you, you bite the bait. Look at how he behaved in front of your son's bus mates and the parents? He doesn't care, but you do. Rise above it. Be the adult here. Think about it....how would you react/respond to a child who is rebelling? This is how you need to look at JA...he's acting like a kid who is afraid of losing his candy or his privileges. Find a way to break this cycle that you both are in. If you don't, it will continue to repeat itself over and over again and I don't think that's what you want, nor is it health for any of you, including your children.
I agree w/the lawyer...sign your son up for the activities. Go to the activities on the weekends you have him and let JA take him on the dates that he has him. Both of you will need to find a way to "share" the custody and the activities at some point. I don't think things will settle down w/JA until the divorce is finalized and about 6-18 months after that. Right now, he's flexing his authority for showmanship to all, including you.
I'm very sorry he's still acting like a JA, but when they are off kilter in the mind, this is how they behave. You might want to read the postings of MYTURNNOW. She had similiar issues w/her h and now after all of this time, he's settled down. It's time to take the boxing gloves off, step outside the ring and allow JA to shadow box w/himself.
I'm very, very sorry this baiting continues and he is making your life miserable...but the old saying "misery loves company"...is so true when it comes to people in crisis. Please, please take care of yourself. Find a support group in your area for parents w/o partners or a divorce support group. There are a number of them in my area and they are basically free and they will help you to work through some of these things that are happening to you. You need someone "live" to talk to you about these things and who better than other parents who have gone through this.
Please try to let it go for today and just relax and enjoy your day.