It's really hard to know if the depression is making you obsess about this situation or if the situation is making you depressed, you know? But either way I feel like this is the kind of situation where some good therapy may actually help. Very goal oriented therapy designed to desensitize your emotional triggers from the person. EMDR and or hypnosis can be helpful here. Some CBT might help too. Then if the situation is causing you to be depressed it may help and if the depression is making you have difficulty with this situation than at least you may reduce the trigger there.

You can do it. Rejection and etc from others is the worse during a depression. ugh. so sorry.