Me or her?

Hi all.. Two years ago i've accidentally met someone at university. But i wasnt attracted anyway.. We started talking for a while and i knew that hes in a relationship.. I tried to avoid him but suddenly i liked him and so did he, we actually had sex and then i got more attached .. The point that he wouldnt leave his girlfriend for my sake because we are different religions... And the country we live in doesnt permit our marriage.. I did my best to avoid him but he always wanted me by his side .. And i couldnt refuse .. Specially he wants to share everything with me.. That makes me feel special.. Nowdays he's asking for travelling abroad and having some fun.. I dnt even know why me!! Its like boy you have a girlfriend and u kno our marriage isnt easy.. I cant let go .. And being with him makes me get attached.. And i always wonder, whom he loves? Me or her? And what should i do.. Do i stay or leave? Please help ..

I forgot to mention that he and his girlfriend attend everythin together.. Birthday, christmas, graduations and parties and all of his pictures with her.. But i've never knew Love would be like this.. And if he loves her why he keeps on chasing me.. Anyway i also forgot to add thaat i tried to ignore him.. I changed my number twice.. I disappeared like million times but there always sonething make all feelings reback in.. And he always tries to reach me and somehow he knows how to reach me very well.. This is not the problem.. The problem that I GET SO MUCH SO MUCH SO MUCH DEPRESSED without him!!! I cant survive.. He MAKES ME FULL OF JOY.. Im not sure whether i love him or i find happiness wherever he exists!! My serious problem is that i still have three years with him at university.. We both study Medicine and same class .. Avoiding him is impossible!!

I take it he's not married. That means he's still available. Handle this situation with care. How? You're educated and a woman - figure it out.