It's nice to read your update H and no, it wasn't too focused on your XW. She is a part of your life. It is OK to still talk/think about her. One day, you might be able to talk/think about her without worrying if you are talking/thinking about her too much. Then you'll know you're properly detached because she is just another person in your life. Also, you can still find your XW attractive without wanting to R with her. I still think my H is the most attractive man I know.
I think you need to reframe the giving the girls back after ten days. You had them for ten days. And because you knew you had to hand them back, you probably made those ten days really count. And when you don't have them, well, I don't know about you, but those GAL activities I forced myself to do at the start, well, they are just habit now. Gym, catching up with friends, snuggling up on the sofa with a book or being able to watch what I want on the TV, have all become part of my day to day when I don't have the girls.
I'm sorry to hear about your younger daughter. She's the same age as my youngest right (9). I think your decision to be cordial with your XW for the girls sake is the right one. Our children are hurting. Their sense of family has been ripped apart and they don't know how to deal with it. They don't have the words to articulate how they are feeling and they don't want to upset the dynamic any more than they have to. So, they bottle it all in and pretend to be ok (same as adults really). I have found that my kids seem happier when they see that my H and I are getting on. They never say anything, but when they see us joking around or simply treating one another like normal people (not being cold and awkward with one another) they just seem happier. On the flip side, D12 is grumpier when she hasn't seen her dad in a while, if she senses tension, or, if in fact, if she senses anything that might indicate more change. All I can do is remind her that she is loved by both of us, use "we" statements as much as I can and make a big deal of consulting him on anything children related (so she can see her dad and I are still a team when it comes to her and her sister).
Glad to see the dating thing is going well for you. I think being honest with what you can and what you can't give is a good policy to have. If you think she is at risk of being hurt, then it isn't fair to let her think you can give more than you can. I remember saying to my H when we started seeing each other that I knew that I wanted to spend time with him today, tomorrow and probably next week, but I couldn't promise more than that. We lasted nearly 17 years and 15 of those were pretty darn good.
