Bloss this must be really difficult for you. But at least your FIL's suffering is over and you and your family can get back to some normality after the funeral. Looking after a seriously ill relative can put huge strains on a family, my mum was looking after my beloved gran just before she died, and it was awful, forever waiting for that dreaded phone call, feeling my life was on hold until she passed away. But once she did die, we were able to grieve and say goodbye, and it was a relief that she didn't have to suffer so much anymore.
I wish you well for the funeral, which is bound to be emotional and tense. Just get through that and things will get better I promise. You must feel emotionally exhausted having to look after your young family as well as your dh. How about making a plan to go on holiday in 3 months time to give yourselves something to look forward to, even if it is only a weekend away.
Wishing you all the best. xx