Recent research has shown that spending quality time with people we care about is the single best predictor of quality of life self-assessment. That means that if people are inviting you to do things, go. If they aren’t, you need to invite them (preparing for a gathering is a good activity booster unto itself) or go to Meetup.com and find a group do something of marginal interest to you, and go there to meet people.
Helping others is also a wonderful way to pull yourself up. if you don’t have personal contacts who can use your help, call the nearest school. They are desperate with budget circumstances; it may mean you have to keep at it, but they want you and the kids need you.