Sounds like the mother of your children has an intimacy disorder and might also be a sex addict.
She might be deeply in love with you, but this might be a compulsive behaviour for her (almost like a semi-conscious self-sabotage).
If I were you I would ensure that she do something drastic to discontinue this. For example, I've started seeing a girl in the last few days, but after she told me something from her past, I won't get into a serious relationship with her unless she does a 10-day residential meditation course with me over Xmas & New Year (
Vipassana Meditation).
With that said, we all reach a point where we've had enough. Maybe she's gone too far.