I don’t blame you for hating his ex and I don’t blame him for stopping you speaking to lads you’ve messed around with. Like you said, he’s got more to deal with than you in terms of numbers and you should take this into account. If you see these people around uni, this cloud will hang over your relationship until you graduate. Two years is a long time to let it bother you before you can leave the past behind truly. That’s why so many girls at Cambridge a) Are virgins b) have 1 or 2 bfs all through uni c) sleep with people outside college who they will rarely see in the bar, lectures, societies and can ignore in Cindies, then if a bf comes along they can shield him from it d) Sleep with whoever takes their fancy, don’t get a bf and leave it behind them after 3 years.
You could either finish the relationship, which obviously you don’t want to do through reading previous posts. Or you could confront the exes. I don’t mean smack them, but look and evaluate. For me, even if my gf had slept with him before, if he turned out to be a skinny, balding, comsci of a man then it wouldn’t bother me. Of course, there’s always the danger he’s Beckham with Stephen Hawking’s mind but this rarely happens. Other than that you could do a big romantic karaoke classic together in Freshers to show the world (exes included) you are truly together.