What Is Going on Here?

After we ate breakfast I told Brian that I had to leave because I going to go home and shower and talk to Rebekah about last night. He drove me to my house because I didn't have my car. When we pulled up to my house he leaned over and gave me a kiss. I kissed him back. I got inside the house and shut the door.
"Ugh!"
"Whats wrong babe?" Stephen said.
What the fuck was he doing here? Shit I am so screwed. Where is Bekah.
I smiled.
"Nothings wrong. Just a rough night."
He walked over to give me a kiss. I walked away hoping he wouldn't notice me not wanting to kiss him.
"Wheres Bekah? I figured she would be here now."
"I don't know. She wasn't here when I got here."
"Then how did you get in?"
"I had your spare key."
"Oh. I forgot I gave you that."
He laughed.
"Well I'm going to take a shower." I said.
"Wait and i'll take one with you."
"Uh. That's ok. I want to take it by myself."
He gave me a weird look. I grabbed some clean clothes out of my room and went into the bathroom and closed the door. I turned on the water and then called Bekah.
"Where the hell are you?"
"Calm down. I'm on my way. I had to put gas in the car." She said.
"I can't calm down. Stephen's here!"
"How did he get in?"
"He had my spare key. I forgot I gave it to him. What if he saw Brian?"
"Well did he say anything?"
"No but I was acting weird because he caught me off guard."
"Ok. Well just calm down. I'll be there in five minutes."
I got in the shower. After my shower I sat in the bathroom for a couple minutes. I heard Bekah moving stuff around in the kitchen and talking to someone that wasn't Stephen. I walked out to see who it was. It was Brian! Stephen was on the couch. I didn't know what to do. I just stood there frozen. Bekah saw my face and she grabbed Brian's arm and mine and we went to my room.
"You left this in my car." Brian said as he gave me a peck on the lips.
"Thanks. I didn't even notice."
"Who was that guy?"
I looked at Bekah and she just shrugged.
"He's my brother." Bekah and I said at the same time.
"Well he's my brother but Tiff just calls him that." Bekah said.
"Oh. Well I'm gonna take off and let you ladies talk." Brian said.
He gave me another quick kiss and then left.
Rebekah and I just stood there for a few minutes trying to process what had just happened.
I am so totally screwed!
"What do I do?" I asked Rebekah?
"I think you should tell Stephen the truth."
"Why do I have to tell him? Why can't I just break up with him?
"I don't know. Do what you think is best."
I went and sat down on the bed.
"What do you think is best?" I asked.
"Just tell him that you met someone else and that its not going to work out anymore."
I thought about it for a minute and then decided that's what I was going to do.
I walked out of my room and into the living room where Stephen was sitting. I smiled at him and sat down. He smiled and put his arm around me.
"We need to talk."