Ok so sleep here has been our single biggest challenge over the last 5 years. DD1 has had a severe sleep allergy since 16 weeks old and she is 5. We had tried all sorts of approaches and in desperation at 2.5 we just gave up and let her come in with us. Some nights this is as early as 10pm and anywhere afterwards. Initially we all got vaguely more sleep than we used to but she was often wakeful or restless in her sleep at best so it wasn't a perfect solution as such however we were all struggling badly and I was really quite deranged to be honest. When we were talking to her she said she was scared of the dark and just wanted cuddles. When we talked about things she said she just wanted me and got really upset at not being able to sleep through.
To be honest I wish we hadn't made a big deal of it as she has quite a bit of anxiety associated with not sleeping through thanks to the unhelpful help we have had. So I would now tend to brush over it and move on. It has been really hard and we have often functioned at a pretty low level but it is getting better. Some things I do to help are cook up big batches of food and freeze them for the harder days. I also try to tag with DH for naps on the weekend, this has been hard as he has had some health issues and has been less able to help. If you have the opportunity for time with other people to help out then I would grab it! Most importantly be kind to yourself - try not to assign blame/guilt/negative thought about it to yourself as it is very easy to slide down from there. Easier said than done.

I hope things improve for you soon.