Along with all the other excellent suggestions already posted here, I would add getting some parenting help, and/or maybe counseling for both you and your teen.

And/or can you get someone, friend, family, teacher, priest, to help you with parenting? Confide in someone that you just are not up to parenting your difficult teen on your own, most people will understand that. Or at least if you can find a "babysitter" to take your teen for one or two week nights, so you have some alone time in your own home. Then maybe find some activity or friend that's constructive and supportive for you to go to one evening during the week or on the weekend.

Help yourself first. You can't be helpful or a good parent unless you get your needs - not wants but NEEDS - taken care of first. Unless you feel like you are taking care of yourself you will most likely continue to feel overwhelmed taking care of a problem teen. Even feeling well, some single parents (and married parents) aren't capable of it. It's no sin to admit what you simply can not do. That's a strength.