If you do find out that he's talking to her, you better be ready to carry out your threat. If not, he'll think you are bluffing and will never believe another threat you make.

I'm really sorry he's behaving this way, but he's in mlc land and they do tend to lie quite a bit.

Please take care of yourself and your family.

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.