Please read & respond!!!!!!

So today was me and my boyfriends 2 year anniversary. Not very long but we’re in high school. Just me actually he just works full time right now. Anyway, today he posted a picture of us to celebrate the hardships and successes we’ve had during our time together. After he posted it, a girl who I don’t know at all DM me and said “about 9 months ago {my boyfriends name} took my virginity. I didn’t know he was with anyone I just wanted to let you know” this broke my heart, I never thought he’d do anything like this at all. He truly is not that kind of guy. He’s lied before, about smoking cigarettes and another kind of important things to me but this was by far the biggest. We had actually been on a break because of the cigarette issue. I may seem overreactive but he had lied to my face about the whole situation and other things. This is completely different though. While on the break, we still talked everyday, talked about working on our future and still were having sex. He blamed it on being drunk and thinking we were never getting back together. So he didn’t cheat on me technically bc we were on a break but he kept it from me for 9 months after I begged for honesty and nothing but the truth. This is also important to me because I was the only girl he had ever been with (we’ve been together from a young age I know this is true) and it just drives me nuts thinking about him with another girl in that special way. He still wants to work things out and thinks this is just another thing to work on but I need advice or some different perspective here please. I turned 18 yesterday so I’ve been really considering my future and this choice could really affect it. Please please please help me ❤️