You know I'd absolutely go with your "gut feeling" of getting the help you need even if that means returning to America (afterall it needn't be forever, unless you want it to be). It's got to be about putting yourself first when things are this bad for you, and if you explained to your husband then I'd hope that he'd understand and want the best for you too.
And, yes, I can imagine you'd miss your husband but if you compare that with not getting any help do you think that maybe it would still be worth it? You did say that it would mean being near to people you love, so a bit of a compensation there?
As for the days if you're on your own I can see that that may be lonely and give you more space for your feelings to surface more but do you think that you could put some plans into place for how you're going to handle these, maybe things to do? You could even talk to the people close to you in America before you go to help work on those plans? And maybe have a support system pre-prepared e.g. if you're finding things relly hard you can telephone x at x o'clock or y at y o'clock.
Do tap yourself into what services you're going to access beforehand though and "start the ball rolling" with them, so as you have a real solid place to start.
It sounds like you do need help and you absolutely deserve to get it, so wherever is best for you is all that matters.

And you know that if the husband is putting up/causing barriers I'm going to be saying that he isn't really worth it, right? So it's all about you now and don't let anything stand in your way. Do what you think is best for YOU.

Best wishes

Alison