Im in love with someone else

I have been with my current girlfriend for about over a year. we honestly might’ve put too much into our relationship in the beginning, promising things young ppl shouldn’t promise each other, planning our wedding when we’re only in high school. saying that we’re each others soulmates when we rlly dont know what we’re doing. I have this best friend Jack, who I’ve been friends with longer than my girlfriend. I’ve known him for about three years. Recently me and jack hungout, and we had an amazing time, after not hanging out for a while. We were laughing and having fun and the entire time I had the urge to kiss him. Now me and Jack have kissed before, and have had some doubts abt whether or not we should date, but we both decided it would be best not to. But recently i feel my feelings for my girlfriend fading. but shes still so attached to me. I feel like we have different wants and interests. hanging out with her is just so much harder than hanging out with jack. jack knows my family, hes so comfortable with them and me and him have been so comfortable with eachother from the get go. I feel horrible because i used to love my girlfriend so much. And i feel like if i breakup with her she might do something bad. and not to mention jack has a boyfriend of 6 months who hes rlly in love with, but jacks also confessed to finding other ppl attractive while him and his boyfriend are dating. But him and my girlfriend are also friends, and im close with my girlfriends friends as well, and i feel like if i broke up with her then they would get on my ***. its jusy i hungout with her and jack in the same day, and when i hungout with her i just wished i was hanging out with jack. Help.