Read what you wrote about your friend. Is a series of short term relationships what you are after? Because - they're fairly easy to find. But does every time you break up from one mean you are a LOSER again? Despite the fact that DHU-41 was TOTALLY wrong for you (and you said it from the beginning) - you seem to suggest that breaking up with her was a loss. And you continued on with her for much longer than you knew was good for you. Because - she was better than nothing. Well - nothing is often much better than someone else.
You really think you are the biggest loser in the divorce??? I DON'T think so and I think your perspective is really off. Having a significant other is NOT all that it's cracked up to be - so - she has a guy. Big deal. You really have no idea what their R is all about and whether he is good for her or whether they fight or whatever. You DID get a financial mess (ex) out of your life so you won there. You DO have very good co-parenting time with your kids - you are doing great there. What makes you believe you are a loser?
Although I am in a Post D relationship - I did my time alone for a few years. And that time was SO good for me. I did not rate myself according to my couples status. In fact - having ex move out and in with the ultimate in controlling women (and a predator) - I knew I dodged a bullet there. Even our children agreed that our home became much more of a haven without dad in it. His depression and anger disrupted our peace on a regular basis.
When I was on my own for the first time - I got stronger. Yes - I spent time in counselling and learned more about myself, more about what I wanted in a partner (if I decided to go there), set goals for my future - things I may not have been able to do with ex. Now that much time has passed - I can honestly say that I am SO glad he is NOT in my life. I could not be doing the things I am doing if he was. I came to a fork in the road. I ended up on the road less travelled but it has been a beautiful journey despite the bumps and ruts in the road.
I hope that counselling will help you develop a better sense of who you are. Remember that you came into this world alone and you will leave it alone. Who you meet along the way can add to your enjoyment or detract from it. (and a 20 year old might be great for one night of enjoyment but REALLY - is THAT what you want? Walk into any bar and you can have it - just protect yourself). You need to build on the things you enjoy and reduce the things you don't enjoy.
I found a renewed love of gardening and started new hobbies Post D. I moved to be further away from the source of my agony (ex) but I don't suggest this until the kids are grown. I learned to check with myself if I was happy in the moment or not. And if not - change what I was doing.
So stop comparing yourself to other people. Some people on this bb have moved on to fulfilling new Rs. Some are just getting their toes wet and testing dating out. Some are thinking about it. Some are content focussing on parenting, work, creating their own lives. Most have learned (or are learning) that they are COMPLETE an happy on their own. Creating lives that are filled with friends, activities, hobbies, etc WITHOUT a significant other.
Stop being so hard on yourself. You have done some work on creating a new life. You go out probably 10 times as much as I do (I have a severely handicapped son that I need to be home for at night yet I don't think I'm a loser because of it). I could be jealous of all your free time and fun. And you've figured out ways to enjoy your great summertime with your girls, earn extra $ with the umpiring, attend dance recitals, plays, parades - from the time my ex left (D was 12 and a world class baton twirler/dancer) - he never attended a single performance of hers. Not you - you are a very involved dad.
SO - pat yourself on the back for all the good things you do. Get CLEAR with yourself about what you really want - and then go after it. Set your goals high. Don't settle.
And if it were me - when my daughter told me about all the great things she is doing with ex's BF (I would not know because my kids are NEVER invited along on any events) - I would say "I'm glad you had a good time. I'm not really comfortable hearing about BF so I'd rather we not talk about it". Maybe not the advice others would give you but that's how I feel and just what I would do. Why tear off the scab just when it starts healing - you start bleeding again.