Hi, don't know if this will help, but two things.

1. I had a very long drawn out divorce process. Got that over and

2. He threatened legal proceedings for more money - went on 13 months UNTIL

I went on the offensive. Basically instead of responding I said enough. Sue me or go away. Nothing for 3 months now. Still not breathing easy, but the point is, the point is . . . .

You could call his bluff. I would suspect that the last thing on this earth he really wants is custody. This is not to make your child a pawn, but ask him what custody would look like to him?