HI LILY,
AS you feel currently leaving not right for you, maybe see your GP/ Dr for individual counselling to see if helps the situation for both. Not sure if he would be willing to participate, but an option to think about. Please, be so mindful of your safety and When at risk try and remove yourself from the situation if possible. Is there anything triggering the abuse? Or does it happen regardless due to possible anger/ frustration issues? could try some local support groups so don't feel isolated, I hope have other support networks too.
Maybe trying to work at the relationship, if felt wished to by having days out together and spending quality time. Very difficult as if feel dependant and 20 years a very long time together. Nobody should have to put up with abuse, so I hope maybe something can be worked out. However, if situation worsen's many shelters can assist and with money worries re getting help. A solution to everything it's finding the right one for yourself and partner.
TAKE CARE
KATE.