Good lord, you've had about three major events all crammed into one short weekend, sweetie. I'm so proud of you for not just cracking up.
At least you had the one giggle, with H avoiding watching you dance. You know he wouldn't have bothered moving if it didn't affect him.
Now about S15...Alison I'm not going to say I know how you feel, because I don't, but I suspect this must be very, very wrenching. Please try not to feel threatened. For one thing, people who aren't raising rebellious, acting-out teenagers have no idea how impossible it is to actually control them. Far from edging you out, my guess is when supercilious H realizes that short of tying S to the bedpost, that he CANNOT control him, he may develop some empathy for you. (I haven't experienced this as a MOM, but my brother was this way growing up, so I have seen it as a sib.)
Please know Alison I'm not trying to discount your feelings, I would be sick if S15 went out of control and I felt like he had to go to XH and the Nasty New Mrs. But I would do it in a heartbeat IF I thought it was best for S.
As to S's comments about punishment, there is probably some truth and there is probably some chain-pulling going on. You know in your heart that your motives are loving and genuine...so you can only pray that he will come around to see that.
I believe so firmly that things eventually work out for the better, I'm sending your those thoughts and hugs. I wish I could do more.