Silver if sharer says to you she is coping, she is probably coping (regardless of what other liveries say. Oh, the bliss of having my own place now and not having to listen to other liveries any more. Although even your own place doesn't remove the bother completely!) It may be that she is having a grumble to other people, because that's what people do, but in actual fact is just fine and finding winter a bit miserable. Many people do.
But if she is going up there every day, and hoss is being fed and mucked out, then really that's all you need atm. Give yourself a break for a bit and let someone else do the hard work for you. Honestly - hoss will be fine! So far I have neglected 4 different horses at different stages of 2 pregnancies, and none of them seem to hold a grudge. They still mug me for polos!
I was back in the saddle at 5 weeks, and hunting again at 3 months, but if you had told me that 2 weeks after my CS I would have laughed my head off at you. Your body recovers very quickly after laying, but you have to give it a good chance to do so in the first few weeks.
Can you not go and talk to your current yard owner about full livery for a little bit, maybe only 2-3 months? I had Big Horse on full livery for a while and it was lovely. I just turned up to ride. Sharer can still ride to keep him fit, and you will have a horse ready for you to escape on once you feel ready. If yard owner does not provide full livery, discuss the possibility of hiring freelance groom - they are charging £7-8ph plus petrol round here, and you would only need a groom for an hour a day max - they should be able to feed, muck out, groom, change rugs and maybe even 15mins lunge in an hour if they are any good. Tell HI its an essential expenditure for the good of your health and you'll do a bit of overtime when you go back to work to cover it.