You have had a very big change in your life recently - getting married.
As much as you might be in love, it is a huge change and adjustment.
Plus you are in school, so I am guessing you don't get a whole lot of sleep and exercise. You don't mention kids, pets, or anyone dependent upon you for care, but perhaps you have that, too?
Your job is way too stressful. If you are able to get your union to help force proper staffing, great. If not, get gone. Sooner rather than later.
The more work you and your colleagues agree to do, the more you will have to do. So you need to start refusing. I don't know that you should get into refusing at this point. You seem to have enough going on, although it sounds like work is maybe your biggest stressor.
If you are serious about being suicidal, you know you need to get to a psychiatrist, social worker, or psychologist immediately, right? No delay, no excuses. It sounds like you have a Hx of SI. Please, please get help for this immediately. There are suicide hotlines, crisis hotlines. Or get to a 12 Step meeting (AA, OA, NA, EA, maybe others). There are some great people at those meetings and even if you aren't alcoholic, addicted to food or narcotics, or don't have trouble handling your emotions, you will find help and understanding at these meetings.
I wish you were close by but I am sending you a virtual hug.
I really am genuinely worried about you, so I hope you will come back and post again soon.