This is such a horrible situation to be in!! My boyfriend's parents are quite similar, in that they'd go insane at me if I cut in their home.. I've done in before but they never knew.. And they always lecture me when they do find out I've cut.
You're not alone in this, honey.. I wish I could give you a proper cuddle! Please, try and get some help with this.. You need to.. I didn't and I soon regretted it.. Please?
You are wanted, hun, by everyone here and your husband. And his family, otherwise, why would they have you there if they didn't like having you there? Silly woman. She deserves a slap. Your husband being supportive is always helpful, and I hope these things can be worked through.
You take care