I went through a similar experience with a high school sweetheart. I am in my thirties. I focus heavily on being a father now (maybe too much), and it’s extremely rewarding. I picked up guitar and took lessons, was introduced to a beginner cover band, and met friends through that. The gym is another big one. For me, exercise makes me feel better mentally in a noticeable lasting way. My advice is to pick up a hard hobby you really enjoy and finding places where people doing that thing would be.