Huge hugs for you to start with, what a lot on your plate and I'm so sorry for your loss
Go gently on yourself right now
please do feel free to post on our loss and miscarriages board too if you wish - lots of support there for you if you need to talk
I've been through the nursery sleep disaster/SA/OT with both of mine and want to reassure you there is light at the end of the tunnel, honestly. The first few weeks are super-rough on the whole family, and I think you have a totally clear idea of why it is happening. For now, I would just go with it. For both your sakes actually I think the extra time spent on love, connection and security will be really important right now. When mine are upset, OT, over-stimulated etc from nursery I do whatever I need to help them settle, be that stay there until they sleep or whatever. Both of them have gone right back to independent sleep when whatever the issue stopping them has passed
I've always just kept trying the usual, but not stressed about it too much when it didn't work for whatever reason. And then they have always surprised me by just settling as usual one night
They and you will get there! Something it may be worth considering though is bringing BT early on nursery days and allowing extra wind down time - a longer more soothing bath, a massage, more books, longer cuddles - or whatever suits your LO. Often their brains are just so wired they need that extra time to chill out enough to settle.
Hope that's some help xx
I'll move this post over to toddler sleep as your LO is over a year now