I'm sorry to hear things haven't improved for you. Unfortunately the downside to having help is they don't necessarily do things the way you want or need.
Although I do think your oh needs to step up a bit it is important to remember that you're both on a bit of a learning curve. These are your first children and you've been thrown in at the deep end with twins. I really had to spell it out to my oh when our boys arrived and they weren't our first children! If I just cried and said I was struggling he would give me a hug and express his concerns but not actually do anything. In retrospect I think I made him feel a but useless by criticising what he did do and so he just waited for step by step instructions! Try not to add worries about your relationship to your load. A really helpful thing we did was to agree not to dwell on any arguments or cross words, recognising that we were both tired and overwhelmed and just letting it go.
I think what you are feeling/experiencing is perfectly normal. Routine is the key but at the same time remember it takes longer to establish with 2. I always felt that I was trying to force one to fit into a routine that suited the other whereas with 1 baby you follow their lead and tweak it slightly to establish a good routine for you both.
After all the debates about twins versus small age gap it probably all comes across as very negative but honestly it isn't. After having 2 singletons and then twins I can honestly say that twins are the best thing ever to happen to me and my partner. We've ridden the storm of endless feeds,nappy changes, reflux, teething, etc and now in terrible 2's territory but we're surviving and love one another. Neither of us are perfect, we've both forgotten what it feels like not to be tired, our house always looks like a tornado has hit but we're together and we're happy.
Going to your mum's may help to give you a break but try not to fall out with your oh about it. He definitely needs to get used to helping through the night, it's only for a short while and will benefit you both.
Take care. Feel free to private message me xx