Dear DD (sorry, this abbreviation sounds better)
I'm glad you met Sophie_M, she gives good advice. I'd like to add by saying firstly there are two problems, your condition, and his
The is an overhead sign in passenger aircraft
"Put oxygen mask on self before helping others"
Which is basically common sense, if you are in a bad way you cannot help others. Are you finding that you are gettng what you need from your current meds and therapy? If not then perhaps you might like to talk the situation over with your medical team to see what's best
Talking about talking what other support do you have -friends -family? People you can lean on? I was lucky when I was suicidal my wife had her mum there to physically help with the household and lend strong emotional support
We got though it all, due to the doctors and my wife
With your husband I guess the very first thing you need to face, like my wife did, is that just one person cannot keep on keeping another alive unless there is a little something in that person. It takes their medical team, people in their life -and their own efforts (even tiny ones) to stay alive
Sophie mentioned Lifeline and the Suicide Call Back Service, These are not just for your husband, but for you too. You do not have to be in a suicidal crisis yourself to talk to these people, you can get practical advice and encouragement too. Just the sound of another voice can make one fell less helpless and alone
What to do? Frankly I think you are doing everything possible already, loving him and letting him know he is loved and you are constant in his life. Encouraging him to seek as much professional help as possible. There is no reason to feel guilt even if he is suffering now and has in the past you cannot see the future
I would not have believed anything except taking my life was possible -never the happy and fulfilled life I have now -and I would have dismissed out of hand any suggestion otherwise.
Sophie mentioned a Safety Plan (It's called BeyondNow). This is good, it fits in a phone and the pair of you can try to fill it in during his better moments, remember the things that made him feel good, laugh or simply forget the misery of life. I've YouTube clips of comedians, music, I have books and movies and more. Be inventive.
To answer your last line try talking of unrelated pleasant soothing things, the sea, animals in the forest ... anything to remind of a bigger better world