Please look after yourself OP. You are a special and valued person.
It is harder than you think to kill yourself. It will probably hurt. A lot. And it will leave a mess in literal and other ways which your loved ones will have to process for the rest of their days. And for the person who finds you if you succeed. And what if you are not 100% successful? It may leave you in a worse place than you are now, but no longer with the physical ability to do anything.
It is NOT like you see it in films and on TV. Generally you don't just take a few pills and fall peacefully into sleep, never to wake. That is not the reality. The reality is frightening and it f~cking hurts.
I am sorry to present things to you in such a stark way. But killing yourself is not the answer. However bleak things seem. The world, and your family's world, is a much better place for having you alive in it.
But I know how it feels. To be so far down at the bottom of a smooth-sided pit that you can't even get a firm finger-hold to try and climb out of it. I have been there. I have attempted suicide - I would have succeeded if it had not been for my dog, who ran off and got help. It has not been easy - I take anti-depressants, I also did cognitive behavioural therapy, which I found very helpful. but I will wholeheartedly say that I am glad I did not succeed. The CBT helped me to get out of the thought spirals that always led me to feel that I had no other option than suicide.
Keep going. Just for a little bit longer. Please do seek the advice of your GP. Life on anti-depressants is manageable. It helps with the physical aspect to the depression we suffer. It can also help to speak to someone about what's going on. Is there any respite available for your husband that could give you a bit of a break - a local men's shed or similar group if he's up to it? You might also find some useful support here: Dementia Support Forum.
Keep posting on here. You clearly have lived a worthwhile life, with family that love you. It won't always be this sh~t. Please, please don't kill yourself. There are better days ahead for you.
Keep going. You deserve your life. Your children deserve you in their lives. 💐 It will be alright - even if it doesn't seem like it at the moment. x