a similar (not as extreme) thing happened to DH and I when a (distant) relative's husband diedwe had to close ranks, and tbh, my lovely H was bloody terrified smile^
we managed to salvage the friendship by nipping the late night requests for washer-fixing etc firmly in the bud at a very early stage, and it has remained strong with no feelings too hurt
A very similar thing happened to us some years ago.
MY DH's friend had just died. My DH initially helped his friend's widow out with a few things, as did I. But this soon progressed to requests to DHonly to call round and fix this, fix that and the other at all times of the day and night . There was some mowing of lawns involved as well if I recall.
But she did have her own lawnmower 
We were getting phone calls up to 3 times a day. (she never seemed to want to speak to me)
My children were young at the time and it was really starting to grate that he was spending so much time (even some Saturdays and Sundays) round another woman's house, when he should have been spending time with us, his family on the weekends.
(she was from a large family so had quite a wide network of support, so there was no need for her continuous requests for DH to go round there)
Things came to a head one Sunday. We were sat down having lunch when she phoned and she wanted him to drop everything, there and then to go and help with some 'emergency'
DH could see I wasn't happy about it and made some half-assed attempt at saying 'no', but DH doesn't like confrontation, so I took the phone off him and politely said ''well, we were in the middle of lunch'' What is the problem exactly? But I've finished mine - Is it something I can help with?
She wouldn't tell me and asked to ''put DH back on''
I said in a firm polite voice ''He's Trying To Eat His Lunch. You will have to phone back . Bye Bye. Speak soon!''
I put the phone down.
The requests dropped off after that.
Looking back, I think if I hadn't taken control of the situation, there was a strong possibility that spending so much time together (combined with her crying a lot and DH being the huggy type and her hitting the wine bottle most nights from what I can gather) things could have progressed to something else.