LL, and you made me apologize for once calling your H "thick"!
Hello LL's H? Anybody home?
What if....what if...you arrange a night for gf to bbsit and tell H that you have a chance to get out for dinner and/or a movie on wednesday (or whatever).
I have a hunch the sooner to the date you tell him the better as if memory serves he's the king of "wait and see".
If he does play a "wait and see"...then take that night and go out WITH gf and have a great time while he watches the kiddos!