I think that sometimes it is about knowing that it is understandable and even normal to be feeling crappy right now. It isn't that there is something abnormal about your feeling that way, the majority of people in comperable situations would feel comperably. I think the idea is that that way... You won't beat yourself up for feeling crappy. You won't feel ashamed or embarrassed or comdemning about your feeling crappy. Instead you can acknowledge the feeling - which tends to help. Beating yourself up (feeling like a freak) - tends to escalate the feeling.

What to do when you are feeling crappy and when you know that you probably will be vulnerable to feeling crappy for a while?

Self soothe and other things that take care of yourself. Exercise can help mood considerably. Socialising with people and having some kind of pleasant interaction with them can help considerably. Having some sense of routine (keeping up with that rather than withdrawing into oneself) can help considerably. Self-soothing... Little things to take care of yourself. Like how if you could imagine some idealised parent... What they would do to take care of you right now. Figuring some of that out and doing it for yourself. Talking to yourself in cooing / soothing tones. Making a hot chocolate or having ice cream. Having a decadent bubblebath with candles and a good book. Little things like that to care for yourself and to soothe yourself and to help yourself feel better.

Hang in there.