To say you are going through a lot right now is an understatement, my thoughts and prayers go out to you and to your family. As a care 'buddy' for a family member who went through a similar process (and is doing very well) I did notice that energy levels definitely had their ups and downs, but you and your husband hang in there - there is light at the end of the tunnel !
Your statement about Seven being "down the road if he was a riding horse" was, I thought, a very honest sharing of where you feel you are at with him at this time. Sometimes we have an emotional attachment to a horse that really makes no logical sense. We all know of someone, or are "guilty" ourselves of hanging in there with a horse that just does not seem worth the time, energy, and sometimes trauma he/she presents.
Is selling or trading Seven an option for you?
If not, is it an option to basically 'let him be' while you are completing your treatment program? You know... the old 'throw the hay' over the fence and make sure his water is good along with his mineral/salt block. "Benign neglect" under these circumstances may have benefits down the road. It can be hard for family members to take over and manage some equine temperaments and also be safe themselves.
You may already be doing that and I apologize if I am not understanding correctly!
If Seven is a horse you want to hang on to, maybe use your treatment time as an opportunity to jot down and list your experiences with him, the training you have done, the results you have seen and your hopes for the future ... rehash the whole thing as your mental energy allows you and focus on your future goals and how/if Seven fits into them.
Maybe Seven is simply remembering the behaviors he practices the most - if that makes sense. If he is a smart little guy, and they usually are, they can be quick to take advantage!
I am such an amateur myself but I do wonder about the kiss on the forehead...maybe, for now, that should be dropped as that may be too much in your space. When you are able to do so, simply brushing him would be comforting to you both. Perhaps tying him up for about 10 - 15 minutes while you putter, or just sit in the barn and watch Mother Nature, would be good for him and remind him that he actually isn't ruler of the universe
Thoughts, prayers, and hugs all going your way and to Seven too !