How long am I going to beat myself up over wasted time?

I'm a horrible whiner. I spend an inordinate amount of time thinking about how much better off I should be in life than I actually am. I have reconnected with a childhood friend recently, and they are at such a good place in life, and I swear it's not jealousy, I do not want what they have, but it just highlights to me all the opportunities that I have squandered. But, I know I can still be successful, but it's very very hard for me to stop living in the past. I don't really know what's wrong with me. I'm feel all alone, no matter how many people surround me.