There's definitely a lot going on in your life right now, and obviously that can bring back a lot of anxiety. Do you still have access to the healthcare at school? It might help you to book therapy sessions just to talk with someone about all this, it could help you feel better. I know that when I am overwhelmed by stress that's what helps the most, and having someone just say "look, it's going to be alright". There's no shame in being stressed in times like these, and you could use someone to support you. Thing is, foods are safe if you prepare them yourself and cook them properly. That would be a healthy way to have some control. Buy dairy and chicken and so on, but tell yourself that since you're the one cooking the chicken you can check every piece to see if it is cooked properly so you'll know you're safe. Make only what you'll eat now, so you don't have to worry about leftovers. You don't have to fear the food and cut them out to feel in control, you need to shift the focus of "control" on quality control of preparation instead of the foods themselves.

Also, relapses happen, don't feel bad about it. It happens to the best of us, even those who are practically over their emet. It doesn't mean you won't get better again! It does feel hopeless sometimes, but you managed to get through it once, you have the strength to do it again I'm sure. What's important now is to take some time to take care of yourself. Find something that makes you feel relaxed, like reading or even just taking a hot bath. Tell yourself it's ok, you stumbled and it happens, you're going through rough times but things will get better.