So stressed I think I may explode, what can I do for some relief from it?

[HeadExplosion]

There's just too much going on in my life at the mo. My best friend has recently been diagnosed with terminal cancer; another best friend has just split (nastily) from her DH; my mum is disabled and currently deteriorating and I am trying to be a part time carer for her; my in-laws are also dealing with a terminal diagnosis and have regular crisis (dread the phone ringing); a new neighbour has just moved next door and is being really vile about our extension which he claims intrudes onto his property by an inch (disclaimer - the extension was built 20 years ago by previous owners and has never been an issue before) and whilst I'm sure he cant really make us demolish it, the bad feeling is horrible. The other next door neighbour meanwhile is now in his 4th year of DIY extension building, which means evenings and weekends are constant banging/drilling (he works in the day) and I don't think I can cope with it all any more. I am already on anti-depressants and just want some relief from the feeling that there are problems every way I turn. There ARE problems every way I turn! Could the doc help? Any miracle 'chill me out' meds I could try? Help.

What a horrible situation, no wonder you are so stressed.
You could try going to the doctors and asking for a referral to a wellbeing counselling service. They may be able to help with coping mechanisms for dealing with the stress. You could also ask for beta blockers to help with anxiety.
Finally you could ask them to refer you to the local authority for a carers assessment to help with looking after your mother. If you are found to have eleigible needs they may be able to help you source alternative care for your mum giving you a bit of a break or put you in touch with other organisations that can help you manage.
It doesn't solve all the problems but it might be a start. Good luck.