I feel very guilty moving away from my single mum after college

My mum and dad brought me to the UK right before I was born but things didn't work out with my dad and he ended up abandoning her here without any help or a right to live here. We had a rough many years as my mum is Russian and couldn't speak very good English for many years, she didn't have a British citizenship and neither did I, and she had no one to look after me whilst she went out to work.
We managed to get back onto our feet when I was 4 or 5 as she managed to go to university here,(she had already gone in Russia but the Soviet Union had just collapsed so she had to move away for work), whilst I was in nursery/school and then she got a job, my dad (not in any contact with by the way) had also agreed to allow me to get a British citizenship when I was 8 so we could finally fly abroad to see her family
During this time she never really had time to find any proper friends, (apart from some Russian speaking ones but there are not many) or a relationship as she was so busy looking after me and working.
I've always been very close with her and she has always been very proud of me but I feel as if the stress from all these years has really messed with her head and she can get very lonely when I'm not at home for long periods of time so she ends up over-reacting a lot and we get into big arguments sometimes.
I'm going to be going university in a years time and I just feel so guilty leaving her on her own for a long time. I'm planning on going to university that is at least 3 hours away and I know I will only be really seeing her on the weekend.
What can I do to stop feeling so guilty? She has just always done so much for me and I feel like if I leave her even more alone she will just end up depressed.