Pommy, I have some thoughts that hit me as I read your post. In no particular order:
Has H been to his GP lately? I know that the NHS takes a different approach to tests than we do here in the US, but I wonder if he is truly clinically depressed and could use some ADs? And/or has low hormone levels? Something feels off and it doesn't necessarily feel like it all has to do with your R. I would believe the storyline that this is depression, not EAP. Until proven otherwise.
Relatedly, is he open to IC? Or will your MC work with both of you individually as well as together (as it relates to your M) so he can get comfortable speaking to a therapist one-on-one and may find that it really isn't as 'scary' as one thinks it is? Sounds like he has some work to do on himself. But MC is a great first step.
Please don't internalize everything that is happening with your R right now as a reflection of something you have or haven't done in this reconciliation process. I think that is an exercise in futility and will only make you feel worse.
Your H came back when you truly dropped the rope. What if you figuratively dropped the rope again? For your own self-worth and protection it might be helpful to pull back far enough so that you are able to collect yourself and act versus reacting to everything H says and does. I am not suggesting that anything changes in your interactions with H, or that he even knows you have dropped the rope, it is really for you, not him.
And like you tell me all the time, you don't have to make a decision about the R today. Try the MC for a few sessions and see if anything enlightening comes of it.
And finally, what can you do today or this week to take care of yourself? Is there a small pleasure you can grant yourself (a glass of wine in the garden, a walk in the countryside, a new book) everyday this week? Sometimes all it takes for me is getting dressed, brushing my hair and putting on my cool sunglasses for a trip to the grocery store (as opposed to shopping on my way home from a run in my exercise clothes). Whatever floats your boat right now, do it.
