I'm glad to read that the children are growing by leaps and bounds and are doing well in school. I'm sorry that their father is such a pita...but as they continue to grow up, they will begin to notice things that just don't click w/their father and what he says and does. It's really a shame.
Now, his comments are more revealing...the wedding has got his knickers in a bunch/twist. He's miserable at home and he doesn't want to see you happy and more importantly married. He figures if he threatens about the support money enough, you'll stay single and he will have you right where he wants you. Can you say "control"? He's lost the plot and doesn't understand that he's lost all control over what you say, do and basically life in total.
Continue as you have been. It's been a heck of a ride for you, but you've come a long way and it looks like things will get so much better for you and the children soon.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
