PLEASE HELP ME WITH GUY ADVICE

so I have had feelings for this guy for a looong time, around a year and a half. we talked for a while over the summer, but he was living in a different place, so nothing really happened. hes back now and last night my friend got his phone number and they started texting (flirtatiously). she tried to hide it from me, but I found out. Should I be upset or let my friend try it out with the guy, even though she knows I have liked him for so long... PLEASE HELP!!