Are there any kid-friendly meetings in your area? I'm betting that's a great way to meet other moms in the same/similar situation. You might meet someone that you can swap babysitting favors so you can widen your circle of support.
Did it occur to you that maybe your son interrupts conversations and talks about inappropriate things because of the dynamic at home?
I wondered this too -& also, is your son imitating your husband's behavior?