Having a teenager can be stressful but it is also a wonderful time to see your child grow into an adult. Have compassion for your child, try to sit in his shoes and see how his life is going. If you have gone from middle to lower class that can be hard for a kid, also if you are dating that may make him feel less important, unwanted.
I dated when my daughter was 15 and she had similar behavior problems, so I decided to wait until she was out of the house. So did I let her "run my life"?, you may say so but she was the child and it was my responsibility to care for her. After she moved out I dated and married, but not before.
You will need to set boundaries, and they will be pushed. It's like having a 2 year old again in many ways. Try to enjoy the wonderful moments until he is gone, but focus on him and how to transition to adulthood. You had the child and it is still your job to do that to the best of your abilities, including making him first until he is grown.
Best of luck.