I have one daughter, 15, and she is currently breaking my heart with her decisions. Regardless, I believe that somehow we will come through it (not unscathed, unfortunately) and I would never ever use even my current bad situation to condemn having children or even just daughters. All children are special. NEVER stop reassuring them that you love them in both words and deeds. In one moment they can misinterpret something and go completely off the rails.
I had my own awful experience with our daughter. From about 14 till she turned 18, she was my heartbreak. She didn't follow our rules, she snuck out at night, constantly ditched school, had questionable "friends". I can't tell you how many nights I drove up and down the neighborhood streets looking for her, or crying myself to sleep because I had no idea where she was. It even got to the point where I was ready to throw her out of the house because I couldn't deal with it any more. We prayed and prayed asking for strength for us and wisdom for her.
I don't recommend this, but what ended up waking her up was she got pregnant. We sat and talked for hours and I asked her if she wanted her baby around those people she hung out with. Without batting an eye, she said "NO" and that was that. She became the person we knew she could be. She married the father (who actually is a really good guy - husband and father), is a wonderful mother to our beautiful granddaughter and that horrible part of her teenage years is just a bad memory.
You just have to hang in there, for her. Even if you don't think she's paying attention, she hears what you say and one day she will appreciate your not giving up on her.