I think about suicide all the time now and it's because I'm trapped in a life (marriage of 25+ years) I should never have gotten into. What to do?

This definitely needs attention very quickly, firstly this needs professional help by visiting the doctor and telling them exactly whats been going on, where they will have advice on the thoughts of suicide and also marriage guidance, if its possible there needs to be some kind of discussion with your partner on the best way to part company as painful as it may be, it will be going forward to a better place, having a good friend you can chat to will be an asset but also using the 7 cups website for support and help, lets fave it when your at this point you need all the help you can get! don't let things get worse your worth more than that.