It is scary b/c you are going into unknown territory again, you want to believe he's changed, but you don't want to get hurt again. But if you don't allow him and accept that he can change, he never will change. I don't know what his motives are behind this - manipulation or true change - but if you want the change to continue, you have to recognize and encourage it. You can tell him that you really appreciate all the effort he is making (recognize it) but still keep the boundaries you need to protect you and S (I thought it was excellent that you set the boundary about staying the night over thanksgiving!) It sounds like he feels you are closing up, which you don't want to do either, but I thought it was good that you reminded him that you needed to take care of S and yourself first. Just remember to continue to watch out for those baby steps (you even said he's talking to OW less - yay!), so don't overlook those in your fear.
So in answer to some of your questions, I think you should avoid the "but" talk of "I want to trust you again BUT I'm scared to get hurt" or "I noticed your changes BUT I'm scared they won't last". It just comes off very negative. Keep the interaction positive with H, but just continue to do what you need to do for you and S.
One last note, I know these more major R conversations are tough, but it's good to sometimes figure out where your at. What you've learned from last night is that he appears to be open to working on your R ("what do I need to do"), but that you are reserved about his changes, right? Hopefully you can avoid the R talk for a while now, but just use it as a learning experience. Also think, what does H need to do for me to trust him again. What particular things would he do (your text to H was an overall description of what you want, but what are the specific things he could do now - action oriented!)? You're doing great though! Unfortunately, I don't think we can avoid heartache completely in all this progress. I know I don't want to get hurt anymore either, but the saying "nothing ventured, nothing gained" comes to mind. But on the other hand, continue to protect you and S, and if you are not in a place to handle that emotional rollcoaster, like right now, H will just have to sit on the back burner.
Hope you're throat is feeling better today. So sorry to hear that S is sick again. =(
Me 27; H 28; S 2 Togeth 9; M 4 Sep 11/14/08 EA OW1 Sep 08 EA OW2 Mar 09 EA OW3 Jun 10