Getting thoughts that destroying me

Hello I am 21 f and my bf 25 m we met online everything was good for weeks until I found dating apps in his phone he started saying that he just want to meet friends and connect with new people he geniunely said that he don't repeat that again after few days he started behaving werid not speaking very angry going out doens't Even come home till next day telling lies I was finding out everything he met some girl he started saying her that he want to live with her moreover he said that he just used me and don't want to stay with me jus used me so he want to get rid of me so he was wantedly doing all the things I don't know how to take it he lied to me and went to her home he is manipulative he changes his words every single day i trusted him he is my first love I need suggestions i couldn't take this betraly lies fake promises he made he was planning to get rid of me now trying so hard for it this is jus main points I was writing here I want someone to speak I want suggestion