Hi Siobhan,
It’s sounds like an incredibly difficult situation you are in. From what you’ve described it does sound like you have misophonia, those are common trigger sounds you describe.
I’m posting a few links for you here in case they’re of any help:
How to discuss misophonia with your partner:
http://allergictosound.com/articles/help-non-misophonia-suffering-partner-deal-with-misophonia/
Some misophonia coping strategies:
http://allergictosound.com/articles/misophonia-coping-strategies/
More misophonia coping strategies:
http://allergictosound.com/articles/the-big-reveal-your-favourite-misophonia-coping-techniques/
There are also some excellent help and support groups online who specialise in self-harm:
https://www.mind.org.uk/information-support/types-of-mental-health-problems/self-harm/#
http://www.harmless.org.uk/
http://www.nshn.co.uk/
https://www.samaritans.org/
Tom