I'm so sorry, OP. That's really tough. Give yourself some time, won't you? I once accompanied a friend grieving something on a trip to Venice, where she'd always wanted to go, and she spent the entire time crying in her room -- it was just too soon, and I think she felt worse because she knew she was supposed to be enjoying herself, and it spoiled Venice for her.
Unexpected delights for me -- travelling around India by train, art, learning new things in an area you're passionate about (I'm planning an art history degree), solitude (I spent some time living on an uninhabited island and was incredibly happy there), moving countries just because I felt like a new place, walking semi-long distance routes, living by the sea, running, learning new skills, taking singing lessons.
I don't at all agree with the people on here who say there's no point in expecting a new place to make you happier because you still have to take out the bins and you bring yourself with you -- I think travel is an incredibly healing and mind-widening experience.
I also think that when coming to terms with not having children you should try to be around people who are leading fulfilling lives without them, whether that's by choice or not. I had my son at 40, and have always had a mix of friends with and without children of their own, but only realised when living in a spectacularly conformist and insular village literally everyone had two children and seemed to spend their time mowing the lawn, cleaning the car and ferrying said children about how difficult it would have been to live there without children if you were sad about it. (We were considered anomalous enough as foreigners with only one child.)
Very best wishes to you.