I waited until some time had passed before I told mine. I felt the same as the OP, that the emotions were raw enough about the breakup between their mom and me, and adding my own true confessions on it would have been a bit much for them to handle.
I waited until we were on a long car trip together and I had them "captive". It could not have gone better. I just said that I wanted them to understand why we split and it was because I was gay. My daughter said "good for you, Dad!", and my son said "Ok, cool. Can I go back to my Nintendo, now?" I also told them that it was completely up to them who (if anyone) they told.
Teens (mine are 18 & 15) will be much more accepting, because in most cases, it's not a big deal to them. I would wait until they seem to be in a better place. They'll bounce back quickly. Good luck!