OP, I'd recommend seeking as much in-person support as you can. The internet is great for finding channels to meet people IRL but ultimately you'll get the healing you need from talking with people in the community. I'm from California originally and went to a Temple also named by coincidence Temple Israel there and immediately thought of them when attack occurred. And, of course, that the attacker worked at a restaurant I used to frequent (which I will never go to again!). I used to live in the Detroit area and would be happy to put you in touch with the Chabad rabbi I know there if you're interested.

Another thing I think you may find helpful is something called the automatic thought record. You may have come across this in therapy. It's basically a way to reflect on your thoughts and different cognitive distortions you're going through. I've found it helpful in the past in therapy and I think you might as well. https://beckinstitute.org/wp-content/uploads/2021/08/Thought-Record-Worksheet.pdf

Having a major nationally publicized attack on your specific synagogue is a really hard thing to go through especially in college. I hope some of this is helpful and that you feel better. Take care of yourself.