Long distance! I need help!

Hey everyone I am in a long distance relationship he lives in South Africa we got bad news about applying for a fiancé visa and ever since it's been hard and things were off... Then I went on vacation and met this guy who Is really awesome and we have been talking a lot! I am really confused on what I should do. I love my boyfriend a lot and we are perfect together but I'm having a hard time commiting after I so easily met someone else who Interest me too.. When I'm still so young how do you know you won't change your mind..... ? Advise please!