Stuck and depressed

I'm in a massive rut one that i just can't seem to get out of!

So im 30 weeks pregnant with my third, my eldest is only two years old, youngest only one. Unfortunately my eldest is currently going through many assessments as there is delay in his development in all areas, to which i believe is autism, but obviously have to await any form of diagnosis.

I used to suffer with depression and mental health problems alot when I was younger and I'm so worried that I could revert back to that stage if things don't change, but there's no possible way that they can so I'm stuck...

Previously me and my two little ones lived in one bed flat in London (but I loved it) I had family just round the corner, I don't drive so public transport was fantastic so I could take the kiddies any where for a day out. There was lots to  do around for the kiddies and I had friends close by. However my youngests father talked about moving to Suffolk (where he lived) and told me all these wonderful things, that his family would be there to support me and the kids, that there was lots for the kids, that i would be able to meet new people ....7 months down the line into moving here and 6 months out of the 7 I have spent stuck confinded in shitty bungalow, there's nothing for me or the kids, nothing is local and his family never come round or call just nothing. I never even viewed the property prior to taking it (yes my own fault) and when I first saw it after signing the contract, I just couldn't believe my partner thought this place was liveable for us. It's like trying to get blood out of a stone for the landlord to do anything, to which I've only recently been told by the estate agents that our landlord is experiencing financial difficulties.

My partner works, so he gets out everyday, to me I see that as a luxury, he then took another weekend night job just so he can afford his eating and smoking habit, so I am always alone with the kids, with no support no nothing. Since moving in with my partner I've found out that he's a complete different person, a compulsive liar, selfish doesn't even come close, greedy, amongst other things.

I'm crying everyday and so exhausted to the point I have no energy and drinking loads of caffeine drinks just so i can function as best as normal, all i want to do is collapse!
I constantly deal with the children, literally 24/7 and currently surviving on 2-3 hour sleep a night, as well as my edelst meltdowns and trying to figure out what it is what he wants as he doesn't talk, nor either of them leave my friggin side, like i have to be in full view during loo trips and baths ....im really trying my best to carry on as normal for my children's sake but I am at breaking point.

I really just want to go back to London where my support net is, but I'm debt up to my eyeballs, don't have the money for a deposit and don't think I could afford the rent for a shitty little place so I'm stuck here, alone with no support no nothing. I just don't know what to do anymore.