First of all, I am sorry for your loss.
I think in your situation I would still be depressed. Losing a child is hard enough and you suffered the breakdown of a relationship and the loss of a long time friend. I think its great that you're going to school. Are there any resources at the college that could help you out? I went through some stuff when I was in school and they had an excellent counselor there that I got to speak to weekly. It was the only time I actually did any sort of therapy and actually felt like I got something out of it.
Are you still on the antidepressants? Also, read up on the implant contraceptive that you have. Sometimes the hormones can cause you to gain weight, or make it really hard to lose weight. If you're not in a relationship right now, maybe think about having it removed. I used hormonal birth control for a long time and it always messed me up.
As for people giving you a hard time for exercising, ignore them. Don't let people hold you back.