Anyone relate?

i have come to terms that i am unhealthily jealous of my best friends boyfriend. 

idk why but its like whenever i see him i feel extreme anger and jealousy. up untill now ( 16 yrs old) i never have had many friends. i was always weird and me and my best friend use to actually hate each other ironically. but she has become close to this boy and apart of me is really really happy for her. like truely. at times i find their relationship cute.however another part of me is filled with ALOT of jealousy and idk why?? hes a nice guy but i just can’t explain it. sometimes i can feel like another person lol and its not that i like him because thats just breaking the first rule of the bestie handbook lmao. i just cant put my finger on why i have this extreme hatred for him?? i dont think i could ever tell her though because it would be so sad for her and also just awkward

sometimes i think abt spreading a rumour abt him to try break them up. or to try set him up. and i remember doing this before when i was younger (12-13)  with my other friend and she ended up breaking up w her boyfriend. i also did another similar thing were i planted cigarettes around the house so my stepdad ( an ex smoker) would get in trouble i was only 13. and believe me I KNOW thats a horrible thing to do and i hate myself for it
but idk what possess me to do such things and sometimes it scares me ALOT. ik ranting here is probs alot so i apologise. i would reach out for help but idk even know how i would vocalise this i haven’t told anyone abt these issues?? do u think this could be signs of extreme jealousy or smthn. i rlly dont want to self diagnose anything just want to get a rough outline of my issue. 

*also pls ignore the title i would be shocked if anyone actually relates to my crazy ass lmao*