Another girl is into my boyfriend.what should i do?wil he fall or stay?

it's me again anyway i met my boyfriend.actually i made a excuse to my mom and told her i had some school stuff and i travelled about 2hours to see him.we seemed eager to meet me as he said.i think now he has less thoughts of having sex before marriage now that i told him i won't do it before marrige and he said he would wait but still wants the whole kissing and touching.while we were just wasting time thinking he suggested we check our mails.out of the blue i see another girls emails who sends him love emails.from what he said she is beautiful but he never emails her back.he says he does not want her.he only wants me. i have heard he ignores some of the girls who like him but im still not sure what to do.later on he shows me that some how she gets his number and txts him.he made me a promise not to ever leave me.but sometimes how can we really trust?i feel so green with jealousy.i never seen her but i can imagine she is beautiful.i love him.im scared and i get so worried that i have dark circles.i cnt hardly concentrate on my study.i argue with my family.my life is a down fall with everything in my life.how can i just forget about thinking of that girl.i told him i don't like it and he said he wants me not her.when ever i think of him i see him in future with me.he even told his brothers that il be their inlaw,he told me several times he wants kids in future,he does little things for me like carrying bags.he said he did it because he was my boyfriend.tells me im sexy to him.and stares sometimes and tels me he loves to.does that mean anything?took me to a temple.but what happens when i go to a different country to visit.can she takeover him?i mean i won't even have a cell fone so i can talk to him.he said he felt the same jealousy when i talked to my friends some of them are guys.sorry u guys for the long story.u can make it ur short version.just please help me with my life.