Obviously, the fact that you were previously married and came into this relationship dragging the baggage of children and an ex-wife is something your W has just not been able to process. Adolescent children aren't cute and cuddly and they are often just a PITA. To allow a teenager to get under your skin to the extent that you call them a "nutjob" is IMO just completely immature behavior. The fact that she said this to you, the child's parent, is completely rude and aggressive behavior. What is her deal? Are you still emotionally involved with your ex-wife and does she sense this?
I think you were wise to call her bluff on leaving. Perhaps, you can continue this strong stand and address your sexual issues also. As long as she's about to leave you for one thing beyond your control, having adolescent children, you might as well bring up the other issue beyond your control, wanting sex. Good Luck!
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver
