What Is Going on Here?

We both sat in silence for a couple minutes and then he asked if he could kiss me again.
“Well… Brian. I’m still dating him.” I said.
“I don’t care.”
He kissed me and I couldn’t help but kiss him back. Things started progressing and then one thing led to another. We were now in my bed room with our clothes off. I kept kissing him and hopped on to the bed.
“Are you sure you want to do this?” He asked.
“Yes.”
He started kissing me again; he made a trail of kisses from my neck to my waistline and back up. Then we started where we left off.
Afterwards we were lying there peacefully.
“So what should I tell Brian?” I asked.
“The truth, he will probably kill me. But you should tell him the truth.”
“Ok. I will tell him in the morning. So are you just staying here tonight?”
“If you want me to.”
“I want you to.”
We fell asleep in each others arms.
The next morning, I woke up and smiled at Zacky. He looked so cute we he was asleep.
I took a shower and walked in the kitchen and got me a glass of orange juice.
Rebekah came walking in with Matt.
“Glad your back.” I Said.
“Hey where’s your phone, I need to see it really quick.” Matt said to Bekah.
“Its in Tiff’s room.” She replied.
I completely forgot about Zacky being in there. I was so occupied on Rebekah being ok.
“Uh. Why is Zacky in your bed…Naked?” Matt asked confused.
“Oh my god. I forgot he was in there. Please don’t say anything to Brian. I want to be the one to tell him. Please you can’t say anything. I am going to tell him later.”
“So what’s going on?” Bekah asked.
“It’s a really long story. I promise I’ll tell you later.”
“Ok. Just please know what you are doing.”
“I do.”
“You know, you and Zacky would make a good couple, probably better than her and Brian. Don’t tell him I said that, but I think you guys would.” Matt said.
I smiled.
“Well thanks.”
He smiled.
“I should probably wake him up and then head over to Brian’s and tell him everything.” I said.
“Ok. Well I was going to go back to Matt’s. If you need anything call me.”
“I will.”
They left and I woke Zacky up. He smiled and kissed me.
“Matt saw you.” I said.
“He what?”
“He walked in here to get Rebekah’s phone and he saw you.”
“What did he say?”
“He said he wouldn’t say anything, because I told him I was getting ready to tell Brian.”
“Oh. Ok. That’s good.”
“Yeah, he also said that we would make a good couple.”
“I think so too.” He said smiling.
“Me too. Well I need to head over to Brian’s to tell him everything. You can stay here or leave. It doesn’t matter.”
“Ok. I’ll probably just go back to my place.”
“Alright, I’ll call you later.
I walked up to Brian’s front door and took a deep breath.
I knocked.
He came down the stairs rubbing his eyes. He probably had just woken up.
He smiled when he saw me.
He kissed me.
“We need to talk.” I said as I walked in the house.
“What’s wrong?”
“We should sit.”
“We went to the living room and sat down.”
“What’s up?”
“I… I cheated on you.” I just came out and said it. I could keep building it up.
”What? With whom?”
“I know. Its crazy. I cant believe I did it, and you probably wont like who it was with.”
“Who was it Tiffany.”
I took a deep breath.
“…Zacky.”