How can i stop matsubating and my sexual urges since i am in teenage and single

Assalamualikum brother and sister, I am so ashamed to share a promblem i am having for about a year. When i was about 14 years old i start matsubating but then i left it when i was in matric. A teacher gave me love letter and said that "she loves me". I was so happy because she was i favorite teacher. After a week she asked permission to kiss me i let her kiss me. Then we start talking late nights about mature things. I didnt knew that i was doing wrong then one day she send me some nudes. About 1 month she kissed me servel times. Then she left me because school was over. But i was fallen in love with her. She deleted her account and i cannot doo anything i miss her alot and i have start matsubating about everyday i am so ashamed that i have started matsubating and i kissed her. In short i have start hateing myself. I want to quiet matsubating and i dont want sex before marriage ad it is haram. I am having a lot of sexual urges i woukd be helpful if yiu have answers for me.