Pls give me some advice... 😩

Hey guys! I dont know who i should talk to about this so thought u guys could help me and give some advice. Around 3 months ago I started dating one guy, (we knew each other since 2011, but just knowing each other. Both study abroad and from different countries). Until we started "officially" dating, we've been hanging out alot since we have common friends and started liking each other. Actually he's the one who was there for me when i was suffering from my heartbreak and he was just so different than the other guys who tried for me. Eventhough he's wayyyy older than me (im 22), he acts like a kid when he's with me and u know something just felt right and i went for it. He attracted me so much. BUT at that time he had a girlfriend but from a different university (kinda far) and she used to come here only during the weekends. Before we started all of these he mentioned about her and at that time i didnt know we'd be this close so i was okay bout it. (We live in the same dormitory) Since we started this, he used to say he would take care of the situation so wanted me to give him some time to sort things out, and was actually trying to push her away. I have never been in a situation like this before so even me i used to say it's better we just stay friends and keep things cool but he refused all the time. So things got way deeper. I've never loved anybody else like i love him, and i know he loves me too. The problem is, he's still with her, and whenever i come up with this topic, now he gets kinda pissed cuz he thinks that im not appreciating his effort. He explained that he cant just say "we're done" to the other girl without any reason/she hasnt done anything. So he just keeps trying to give her the idea but still inside im suffering from knowing that there is still somebody out there. Even some of her clothes n stuff are here and i get to wake up every morning seeing those things. What should i do? I seriously need somebody to talk bout this since i cant tell this to my friends here... PLEASE HELP!Â