Best Friend Betrayal?

I normally wouldn't have done this, however I find it prudent for this question to be asked. First some background information. My friend and I have been friends since the 7th grade, I am now 21 and she is nearing 21 as well. In the 8th grade, the guy I was currently dating cheated on me with her. I don't know the details nor do I want to. However, I started to date a new guy in high school, we were together for 3 years and when we split I was devastated. 2 years after that, we'll call it present day, she goes to his house and does drugs and sleeps with him. Now, I'll call him my first love because I did what you normally do in a relationship during high school with someone you think you love and lost my virginity to him and he lost his to me. My question is, is it wrong/bad that I am furious with her for 1) not talking to me beforehand and 2) betraying my trust by not telling me right off the bat when it happened? (I found out from my twin sister.)