You've had a dad and three stepdads, and your mom has already left the latest and is moving on to the next guy. And you're suicidal. OK, wow, that's a lot.
So, I'm thinking that your mom has got something going on mentally that is causing her to be unstable and to move from man to man. How long does she last with any one of them? Three years maybe? I'm wondering if she's bipolar. Look it up and see if it fits.
Here's the bad part... you might be feeling unstable because it's in your genes. You can fight that, but it will be tough. You need to get evaluated by a doctor. If your mother won't take you, find a way to get to a doctor by yourself. Call a hotline, call the doctor, do what you have to do.
If you do have something, there are meds and therapy. And watching your mother, you can know what to look out for.
Maybe I'm wrong. But it's worth seeing a doctor to figure it out.
Watch the videos at www.itgetsbetter.org to see if someone's situation inspires you. And make plans to get out by moving out, going to college, living with someone else, anything but suicide. That doesn't fix anything.