This situation happened pretty recently my ex broke up with me and I was trying to look for a new person to move on from my dumb ex.

I started hanging out with a close friend I had my freshman year of highschool I'll call him E for this story (I'm now a junior(also back then I had a huge crush on him and considered him "my first love")) and after a few weeks his friend, T, said he was intrested me after a couple weeks of hanging out.

Everything was going well for the first few months I would talk to T daily and we were both sure we were going to date soon. I kept using words like "When we date..." and "I really like you" "I miss you". Until something strange happened. We were in the back of T's car and somehow we all started making out with each other E kissing T me kissing E and T.

After that day E started texting me a lot more often and I soon realized I really liked him, more than T. Which left me in a predicament because I had to choose between the two of them. E and I kept our 'relationship' a secret for a while in front of T, for example when ever he wanted to hold hands I'd cover the hand holding with my leg or if he went inside a gas station when we stopped we would let go when we saw him come out the door. 

Of course T wasn't too dumb and eventually realized what was going on he expressed his dismay and how upset he was to me and E's sister. He ended up calling me a whore. Am I the asshole in this situation?
TLDR; I led on a guy for a few months and ended up with their best friend.