Steve,
Can I just start by saying thanks for a great series of posts about your skiing weekend. If your comments and quotes are reasonably accurate, then I suspect your weekend will take a while to truly process properly. All three of you behaved in ways which were subtly different and which together may create some problems for you in the future.
First of all, Sue took the lead role with you in a far firmer way than before, albeit softening the edges sometimes when she thought she might have gone too far or too fast. Her vision of what she wants from you is hardening and she is quite open about what pleasure she wants from you. I think this over time is going to become very hard to take. Previously, your reconnections have allowed you to show her that you can give her just as much pleasure as before. Now, you won't be able to unless she asks. It seems that she is going to need to, or want to ask often. Remember, this is early days, the whole thing is still exciting for you. That will wear off sooner than you think.
Secondly, Paul is starting to see more of what Sue wants and what she wants from you. I would be amazed if she hasn't shared with him what she has said to you. He is totally focused on giving her what she wants, even if he thinks it is in conflict with what you want. He is still asking if you are ok, but this will decrease. He is also, it seems, starting to get off a little showing you just how well he can both make love to and fuck Sue. The two things are different and the former is more dangerous than the power fucks and super orgasms they create. Whatever Sue may say or think, Paul must be starting to have some special feelings for Sue. Maybe not love yet, but that may come and all men can get sneaky when that happens. Watch out for it, Sue may not see the signs as well as you do sometimes, but I suspect he will become guarded in what he starts to say with you around when it happens.
Lastly, you seem to be struggling in your beta role of focusing on your wife, being loving if not sexual with her, and not interfering with her time with Paul. You continue to deny yourself release, which makes any remaining times you get with Sue become desperate fucks allowing your release. Sue knows she isn't going to get anything out of that, and lovingly says it's ok maybe because she thinks you might have some guilt because of it. On your narrative, she is struggling to see the loving. You getting excited by him fucking her, you egging him on like some frat buddy (if in doubt say nothing), you desperate for release with her. It's not a good picture. Maybe you should have released it all first on the couch on Saturday and used your time to make slow love, not intended to satisfy primarily instead. That would have been a better reconnection for her. Not competing with him but giving her something that he cannot provide or she doesn't yet want to take from him. Pure love, undisturbed by passion. The pace would be dictated by Sue. If she wanted it to lead to something more, it would be up to her. If it was so slow you didn't get off, you finish it by hand again. It would all show her your loving, beta role.
I suspect I have overstated my case a bit because you have not given us all of the loving narrative you share in reality. Maybe you can tell us where you think the balance really is.