I have to watch my diet / stress levels a lot because I can change from being a lovely empathetic person one minute to a complete miserable grumpy arse the next, lack of sleep, to much training, needing a holiday / break.
Also try not to be too hard on yourself, maybe a lot of your ex-friends deserved the heave-ho and your better off without them.
Find a new mindset and make a fresh start, address the fundamental issues in your life that are making you miserable, and look for people in your life who make you happy. Good Luck!