Your sister - I'm really sorry to hear that, is she in full time care now? I know it hurts when someone you love doesn't recognise you, I found that focusing on the good times and the memories we made helped me.
Your flat - Were you insured at all? I'd talk to CAB about that, even if you're not insured then try to find out if the landlord is.
Your son - He's paying is dues and hopefully that will be a lesson learned to him.
Your husband - I suspect that your husband is feeling the clench of guilt around his heart that his Dad has died without them ever having rectified their differences. Try to be understanding about what he's feeling and suggest he see a counsellor.
Your car - I'm guessing you don't have the spare cash to have it repaired. If you don't want to sell it, then invest in a bus / train pass for the timebeing.
Loan - You're in the same situation as the majoriy of the Country, so long as you can afford the re-payments then you're fine, if not, can you talk with your daughter and see about splitting the costs and giving back the loan to the bank?
The temple - That's not just your resopnsibility to find a place for the couple to marry, I wouldn't dream of having my parents pick a venue, why can't they do that?
Your work - What do you do? Is there an option for climbing the ladder or moving to another Comapny that will pay better than that and have a 40 hour working week??
Son's g/f - Telling you not to worry is like asking me not to eat, it can't be done. Can you sit her down and tell her you're concerned? I dubt very much she would change her style because that's who she is, but maybe she can help ease your mind.
Give away - Did you mean your husband is NOT going to the wedding? Do you know it's not law for the father to give her away, you can too....
What is the motives of the man who is interested