I know what you mean about gifts so I can't be a help there. I think it's great that you are helping out with the wedding and taking some of the pressure off of your friend and his bride.
I glad to see that your X is taking things better than she had in the past and maybe she is "moving on" or God is working in her heart. Who knows for sure but it definitely would be a good thing for you, your kids, and even your X.