Sounds like you're all very young. Those "relationships" are seldom long lived. Your friend obviously wasn't worried if going out with him would damage your friendship .. So you should do what you like. Immaturity can make life very complicated.
There's this guy that I've had a crush on for like forever. Recently he asked my best friend out instead of me.Their "relationship" only lasted a week. He's very flirty with me, is it wrong if I go out with him? It's very complicated...