Sadness is okay. Anger is okay. Despair is okay. Loneliness is okay. Stop trying to suppress "bad" feelings and just let them do their thing. They exist for a reason.
I mean to feel the loneliness and not try to immediately unfeel it; not try to mask its odor with some other feeling like anger, competitiveness, anxiety, ignorance, stress, arrogance, jealousy, martyrdom, depression, remorse, nosta...
If you're feeling bad about yourself, keep in mind that Brad Pitt is engaged to Billy Bob Thornton's sloppy seconds.
One day you may feel healed, the next day you may want to kill yourself. This road is a bumpy one, full of twists and turns. Every day will not be a good day. Every day will not be a bad one, either. Healing is not linear.
One minute they can be happy and the next minute very sad and withdrawn which is not always the result of how they actually feel but what they have picked up in others, this can be confusing let alone depressing.