"Hey, Ileana!" Well, you've got yourself a sticky situation here!!! Not to worry, though.

First, I'm wondering why your friendship isn't strong enough for you to tell your friend that the guy she's crushing on has a girlfriend??? Yeah, it will be a let down for her, but why should she call off your friendship over something that doesn't even have anything to do with you???

So..... what do you do??? It would be easy to just pretend you didn't know that he already had someone in his life, but from what you've said you don't want to see your friend get hurt. I understand that and I think you're a great friend for trying to protect her. So, since you're such a great friend I think the only thing you can do is tell her the truth. I know it's hard but you'll be doing the right thing.

Now, what happens to your friendship??? Well, it's really up to your friend. If she's gonna freak out and blame it on you she's really not being a good friend. There's a good chance she'll be mad. She'll probably take it out on you, but I'm sure when she cools down and comes to her senses she'll realize that you were only trying to help. It may take a while but no matter what
happens you know you did the right thing.

I hope this helps!!!