Look, if you're here you probably have already enough to deal with. I totally agree with kaliope. I'm sorry, I don't want to sound harsh... but from what I read I feel like asking if this relationship is doing you any good.

Have in mind that your husband is not supposed to "help" you, he's supposed to take care of his son and it's not like if he was doing you a favor. Have you already made this clear? I'm sorry, but you should be getting more support from him (besides him taking care of the baby, which is not to be considered support from my POV, it's his duty!).

As for the friend, does your husband know how overloaded you are? Can't you ask the other guy to leave and tell him you have a small child to take care of? If not, then let the girl bother her parents. Ignore her, she's not her responsability as her father is right there.