Struggling to support my partner.

Hello, new to this space and seeking guidance on my current situation with my partner. A little back story we have been struggling with highs and lows for quite sometime. We’ve been together nearly 11 years. We both had a share of struggles during this time. We have a son and another child nearly due. I’ve been off work for nearly a month now as my partner has been struggling with daily life. Their mental health has been on a downward for a while and it has got much worse. They’ve recently came home from hospital after they attempted to end their life. We have extensive support from the hospital and they have been great. But since they’ve been home things are getting harder again, for a long while now I haven’t had any say over our son, from the smallest things like dressing him, which park we take him to, what food he eats, to bigger stuff like when I can visit my family with him, my partner panics over anything I want to do with my son it makes me feel so useless and not trusted. Since I had time alone with my son when they was in hospital I felt like I was able to parent for the first time in ages. So when they came back home the controlling behaviour started immediately and I was met with a lot of criticism. it made me upset pretty quickly. Which now has caused a lot of tension in the the house.I feel now I haven’t got the energy in me to be present anymore I can’t sit through anymore talks to help I just get too upset. I feel guilty for running out of steam and I know my partner is going through a lot right now. We have talked about how I am feeling and my partner is aware on the pressure I’m feeling and the controlling habits over our son how I can’t parent. They say they working on it and they want to get better, but I have to be more supportive and let it go. Which I find hard to do right now I feel if I keep enabling this behaviour it certainly wouldn’t help. So I’m very stuck and unsure how I can help from here. There’s other struggles my partner is facing right now but this one in particular is really difficult for me I’m not coping well. Hope this doesn’t sound like a “rant” I’m just not sure where to go.