It is normal to suffer from self-doubt after such an experience. You will simply have to work at that. I would very strongly recommend it. I know that I thought I would never even think straight again, let alone get my self-esteem back on line. Therapy helped, enormously.
Compassion is a wonderful trait.
Nothing wrong with it. I feel that here it has connection with your damaged self-esteem. No one needs to be lonely - people are there and you would be surprised at how glad they are to reach out too. You ask for survivor's wisdom. I can tell you I also thought I'd never feel like talking to anyone again, yet I have been so surprised and overcome at the goodness I have encountered.