Perhaps your mom was not upset by your acne but by the way you are handling and responding to it? Not that this would make what she said ok.

I'm very sorry your mom hurt you. When I'm in a bad episode I can say hurtful things I do not mean at all. This is not me blaming bipolar, it's a legitimate medical problem. I would be horrified if I said something like that to my child or made my child feel as you are feeling now. I cannot speak on behalf of your mother though.

I'm truly sorry for everything. I battled acne for awhile until I found what works to control it for me and it was very difficult. It can really effect your self esteem and lifelong prognosis. (((Hugs)))