I'm in the same boat. Working in a restaurant my BW works long hours. Her days off are usually wednesdays and sundays. But, I'm getting used to it. If and when she decides to go away for the weekend with me, it will probably be a tues/wed/thurs. So what. Things are cheaper and less crowded during the week anyway than on the weekend. I've started taking DS down to her restaurant friday and/or saturday eve as well. So we get to eat and watch her do her thing.
Maybe you could meet him at his job some of the other days for lunch or coffee breaks or something?
I, too, lost my BFF (he was AP's H). I also gave up my main hobby, which was my choice, but I have a lot of free time now. I spend it cleaning and playing video games. I don't know if you work or not, but that might be something to consider. If you need to be home for DD there are a variety of things you could do from home for extra cash and to keep busy.
Right now my priority is my family and BW. If she decides she wants to spend time with me I want to be available for that. It's not easy to make friends when you're working from home though, which is my problem. I doubt I'll find a new bro on my own, but perhaps we'll make friends with another couple someday.
Sometimes DS plays outside with the neighbor kids and I'll sit outside with the adults while the kids play. So, for now, that's my socializing.
Anyway, I know how you feel. "You've been heard"