Friendship Jealousy

Do you guys experience this? Like your bestfriend having another friends and you feel like they're only yours?

I have a bestfriend that told me he has new 4 bestfriends and close with them the same way we are ( we are friends for 10 yrs, he only know them for months) but for me, he's my only one. I felt like shit about it but never told him so I just started being close to other people and found someone which I will call A, that vibes with me.

A and I ended up being close in just a short time. We are always talking, gaming,hanging out, and my bestfriend got jealous bout it(his friend told me) and he feels like as if I'm replacing him.I thought since he has other bestfriends , I will just invest time in other people