L.S.
First, know that you are not alone. Everyone with teenagers go thru the same thing. Children are very selfish. They don't do it on purpose, it is just that they are the center of their universe. They don't realize the things they do or say, they only know how it affects them. One day they will be wiser, and understand life more and realize that some of the things they did or said were wrong. But for now, they are being typical teenagers.
Try not to let their actions affect you in a negative way. You can't control other people's actions, you can only control the way YOU react to them. You are wiser, you have to realize that they are still children and really do not mean things they may say or do.
In the end, the only thing you can do is to try and teach them as best as you can and hope that they make the right decisions when those important moment in life arise. You can only guide them in the right direction, they have to learn their own lessons in life.
Good luck, and take a deep breath, things could be worse. I lost my mother when she was 53 to breast cancer.
Cherish every moment.