Sounds like you are doing very, very well in your recovery and he isn't. He had the choice to go into recovery and grow and heal with you but instead he chooses to stay on this path of addiction and destruction. I am sure he resents the fact that you are now sober and doing well. Unless and until he ever decided to get sober he would only try and drag you down into addiction again to feel better about himself and his own using. Yes, it is common for addicts to run out and find another GF. At 19 she is very young and probally naive to addiction and all of its horrors...in a way we should actually pity her for the nightmare she is going to endure with him. Trust me you don't want this man back on drugs and what your feeling is normal jealousy but when you really think about it...it is his loss and your gain that he has gone on to the next victim. Keep on doing well with your life, school and your recovery because in the end your success will speak volumes. My feeling is you will meet another who is now more suited to your recovery lifestyle and who will be able to share and support you in that. You are doing great just keep on keeping on,,,,,,,,,