Help with my resignation letter

So I currently work in a care home and I want to resign ASAP I have an interview today and if o get the job I’m putting in my notice. I have worked at the same place for two years and only ever had 3 days off due to sickness. They have recently employed new people who have never worked in care before and have been making up a lot of lies about me saying I don’t do my job properly and that I don’t look after people properly and that I never come in for shifts and I am always off even though I haven’t been off in a year and half. I do all my work aswell as everyone else’s and I have never before in my life had a complaint. These girls are horrible to everyone and we work night shifts all’s they do is sleep all night and eat. They keep making false accusations against me and getting me in trouble I am now on a last warning and done nothing wrong. I have shown management videos and photographes of these members off staff sleeping on shift and eating residents food and all’s I have gotten back is that they have kids there going to be tired and they deleted the photos. There are 40 people in our home and when I am on shift with these people it is only me caring for them but then I get in trouble when things are not done but that’s because I am physically unable to do everything in the workplace. If they aren’t sleeping they are stood outside smoking but seem to get away with everything and never get in trouble. My mental health has seriously been affected by their accusations and I want to leave immediately. What can I say in my resignation letter and do I still have to give notice even though I have been treated this way and in a bad mental state.