I have to say that I needed a whole range of new strategies when dds were teens.
Most important is picking which battles to fight. I'd advise on being prepared to give up on anything that only really affects your teen.e.g how tidy their room is, whether they are wearing a jumper in winter, what time they go to bed, whether they eat 4 chocolate biscuits for breakfast... etc
Save your energy for matters of personal safety, matters of family harmony, and one or two big rules e.g no smoking in the house, respect for your grandmother
I would also advise being entirely flexible with your time - if there is a small time when they will talk to you, engage with you, laugh with you. then drop everything else instantly and grab that moment and enjoy it. You may need to store up those precious memories to get through some of the rest.
Find a great friend who is going through the same as you, so you don't feel isolated and sad and a failure. You may find that other parents never disclose about their suicidal son, their chain smoking daughter, or their delinquent teens, but instead they will tell you about Jocasta's wonderful cross country running record, or John's amazing guitar talent.
Find your own space and your own strength. You have been (and still are) a wonderful Mum, and a wonderful person.