Firstly, you haven't let anyone down and its not silly. It's an incredibly complex network of emotions and (as you said) coping mechanisms.
Do you have any idea why you're feeling this way again?
You could maybe make an appointment with your GP and tell them you want to hget a handle on it before it becomes a problem?
If not then maybe think back and see if you can remember all the little things you did to get back on track last time??
The only bit of advice I would give is to be as honest as you can with your husband.
I really do feel for you, I recently (sort of) relapsed after years SH free and came back on here for support. But please believe me when I say you haven't let anyone down. It's just a little slip to test you but you're strength and love for your family will get you through.
Xx