Relationship advice

hey guys,

so im new here and i need a relationship advice. im gonna tell you the whole story which is long since we date already 7 months because i want you to understand it all and tell me what u wouldve done and if i did something wrong or him and ik the beginning is kinda boring but trust me it gets interesting kinda in the middle or in the end after i found out he was lying to me so please read it. so the day we started dating he told me abt his girlbestfriend, i was like okay because i have guy friends too so it should be fine, right? but so u understand it u can say im an innocent person compared to him, i drink rarely while he and his friends smoked weed atleast once a week, you know they were „cool“ people. and i also arent close with my guy friends like we dont even meet after school or drink from the same water bottle. so anyway when i met her she was also weird in a good way like my boyfriend and i was surprised that she was nice and we understood eachother. after some time, not long my bf got my hoodie and he said i could have one of his too, i chose one that was lying on the bed because i wanted to take one he already wore and smelled like him and i wore the hoodie everyday and some days later i was at his place and his girl bestfriend was also there and she asked my boyfriend when will she get the hoodie back that i was wearing, i was kinda confused why they share clothes but i didnt wanna say anything since it was only the beginning of our relationship and i thought i should accept her since she was a part of his life and it hasnt been that bad i thought. then like few days later or smth, i dont really remember how long after we dated but still in the first or second month of our dating, he asked me if it would be okay if she slept at his place. in my mind i was like wtf but im a shy person and like i said i was scared to say anything since we started dating eventhough it was crossing my boundaries because i didnt want him to feel like in a prison while dating me and not being able to do the stuff he did before, so i said yes and that night ive been crying until i felt asleep. i told him like few days later that i dont want them to have sleepovers and he said it was okay and he wont do it anymore. another time when me and her where at his place his mom only cooked dinner for me and him, so guess what happened. he gave her his plate and ate her leftovers. i didnt like it either like the other stuff they did but after i think 3 or 4 months, i really realised how much i hated her, before it has been just making me uncomfortable what they did but it has been okayyy but then it was too much. after school started they were in the same classes so both of them had two first hours free on wednesdays and guess what, she was going to his place at idk 7am till 9am when school starts and they spend those hours together alone in his room. and if u think he was cheating no he wasnt but knowing another girl is at his place made my blood boil. and i knew it all was enough when one day we planned to go to a river, me, him, his friends and ofc her. and he was planning to pick me up from trainstation since i live in another town and he and me would get there like one hours after all of the others got there. and you know who didnt like him coming later? his girl best friend called me and told me to tell him that ill come later so i would come when they would be already going home from there. and since i was still to shy i had done it but when he picked me up i cried and told him everything, i told him everything that bothered me abt her and he told me he would break up contact with her. he couldnt manage to do it eventhough i was begging him to do that because i just started to hate her so much that only seeing her once at school made my day bad, i was crying myself to sleep everynight and he lied abt 2 or 3 times that he broke contact with her. and then i had enough i broke up with him because i didnt want him to lie to me just to spend time with another girl, especcially her since while they were friends it really felt like we 3 would be dating and not only me and him. after not even a week he told me that he would now really do it only if i promise him we would get back together, so i said yes because i really love him. it was a monday and on saturday he was going to a party, i didnt want him to but i cant just tell him i dont want him to go there so i said okay. and next day i checked his snapchat account since i have his account and he has mine and i saw he and his girl best friend were texting eventhough im the day we got back together he told me he would block her, i read the messages and found out the whole week we have been together again he spend the lunch breaks with her and that she was at the party too and wanted to sleep after the party at his place but he said no. i spoke abt it with him and he was sorry that he spent time with her again and he wouldnt do that again. after winterbreak, the first day of school he told me she came to him but he wont spend any time with her anymore. now its the end of january and today i found out abt 2 days ago they sat together in bus while going home, ik she went to her place after going with the bus and not his place because i was at his place abt 30 minutes after he got there after school but i dont understand why he is still lying to me, and why do i have to find everything out on his snapchat? why cant he just end their friendship? especially when he told me she spread gossip abt me and him.