Just my 2 cents, and counseling helped me tremendously with this...but I would say you need to cut off all contact w/ X and build some FIRM boundaries. No contact will allow you to get clear on who he is and how he is treating you. No contact will allow you to grow strong without him and find ways to cope on your own. His visits w/ the girls don't really have to involve you.
If you do this, and give it time, you will be amazed at what you can do and accomplish and feel w/o X. But you need to give it time.
A BOB can help w/ the loneliness. (boyfriend on batteries)
You need to love YOURSELF and then get clear and strong. This is how you can grow.
Your advice about him needing down time alone away from you and OW goes equally well for you.
Again, just 2 cents,
SG
Survival Goddess "The most common way people give up their power is by thinking they don't have any." -Alice Walker
