I guess it depends on how close to the end of your rope you are and how much you've been able to get through to your husband that that's where you are.

If it were me and I had had too many conversations, but I was still the one picking up most of the pieces, I would do a spreadsheet - (don't judge me, it really helps me!) Something needs to change and sometimes seeing things in clear terms like this can help get the message across. You can keep things as they are but you might lose your job, your MIL (through choking etc) & your marriage. One of you could give up work and claim carers allowance and get £128 of part time work but she'd be safe & you're time together would be managed around meal times so no call outs. You could increase the carers which would have the same effect but obviously there would be x or y cost and it's not available locally so you might have to increase it more than you'd like (we found they couldn't help for the odd hours or just weekends but could provide help for a 'larger order' as it were.) She could have a live in carer so she'd be safe & you both would have peace of mind but it's expensive and you'd still have bills and living expenses & there's no back up if they leave or are ill (or pay extra for an agency). Or you could find 3 homes say, giving a range of cost options, and wouldn't have extra expenses but would have the back up etc. Each option has costs, benefits and consequences. Here you are husband - which one of these do you want to advise her to choose?

Obviously there might be more or less options depending on if she is self funding or not and how much you think she is really at risk. If I thought my MIL was really unsafe and needed an assessment etc, I would say that you are not responsible for the consequences if they choose not to have one, or to delay it because they don't happen overnight. My dad is expected to wait at least 12 weeks for someone to be appointed as his social worker. It won't be an easy conversation but I get the feeling that if you don't put your foot down, you'll still be needing to be called away from work months and months from now, if something serious doesn't happen in the meantime. Your own parents deserve some of your time too.