Guy's Behavior

What does it mean when his friend nudges him and notices but its complicated?

literally this just happened and i really want to know, i was going home to lunch and i see him and his friend walking the same way and there's groups of people walking also. im right behind them walking and his friend i think sees me and he nudges his arm secretly but you can clearly tell, he then takes the nudge and i see he kinda turns his head quickly to look behind him for a quick second to see. now i can kind of get that nudge meant "oh look she's behind you" or something but what i don't get what it clearly means help! here's where it get complicated though. i liked this guy and my best friend knew all ab him. we fell off in the most toxic way and now she's friends with him and his friend.. assuming, i think she has either told them about me in the worst way possible or she talked about me liking him or even both. before this i always told her i sensed him liking me back and i can see hints but i always doubted them. i don't know what this means, ideas?
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update: i went back to school from lunch and my ex friend, the guy, and his friend are all walking back too and they def noticed me walking on the opposite side of the street next to me and by the entrance of the school they were behind me, after walking for a bit my ex friend goes to him "go get your girl" as again, i was in front of them and i can tell they acknowledge me there.. his friend said something too but i forgot but it was corresponding to what it seems to be about me? idkkk
What does it mean when his friend nudges him and notices but its complicated?
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