redeveloping an eating disorder

A week ago I became very depressed while awake really late at night just thinking about everything that's going on in my life and the pressure I feel. I lost my appetite (which is normal when I'm depressed) but now it's been a week since I last ate and I never meant for this to happen. I have a history with anorexia but I thought I had overcame it. I'm still depressed but every time I try eating something because I think I should I feel guilty and nauseous and I think I'm going right back to how I used to be. my biggest fear is that this will make me more depressed and lead me back to self harm too. how do I stop this before I get worse?