Poly relationships that last seem to start best with a solid foundation of honesty, respect, communication and time management. How are you doing with these... the time management sounds off no?
I think I would suggest getting some help with looking after the kids and plan some dates with your husband first off. It sounds like you don't see the man you have in your life more than you need another man. Think how hurt your man would be if you suggest this too him when he quite possibly misses you too.
See what changes come just be tweeking your existing situation first, before jumping into adding partners. That is what I would do anyway.
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