So I know this isn't as dramatic as some of the posts here but I'm curious for your opinions.

My brother 29M's fiancee 24F has been trying to prank me 23M forever. I don't get startled easily so she has decided on her own to take up the challenge of being the person who successfully scares me.

I never prank her back, but sometimes I'll play along with her attempts. She doesn't do this often. Previous pranks are hiding behind a door/car/in a closet and jumping out at me so it's never anything elaborate.

They've been together 3 years. Never had any problems with them, but she tried to prank me last night and now my brother is upset about it.

Both my brother and his fiancee are currently crashing at my apartment because they are in the process of moving into their first home in my city.

The prank: she hid under my bed while I was out for a run in the evening. When I got back, before I went into the shower, I was at my bedside table taking my watch off and dropping it on the charger. The room was dark except for my lamp so I didn't notice anyone under my bed.

She touched my foot. It was a really light graze so it didn't register with me. I stepped back and squatted down so I could see under there a little. It was dark but I could see long hair. A part of me just knew it was her because no one else would do this. I said something like '[her name] I can see you under there.. but who's the other one?'

This scared her. In her panic she struggled to get out from under the bed all while asking me 'what do you mean?!'. She scrambled out and slammed into me. She also screamed which made my brother come into the room. She was in my arms. I take it, this is why he's mad.

I tried to explain I was just fucking with her because she was clearly trying to prank me.

He thinks I'm flirting with his fiancee, that apparently this has been going on 'for a while' since these pranks began.

I told him the pranks are his fiancee's idea and he should be having this conversation with her, not me. It's been really awkward between us now. I have 2 more weeks with them. I feel like they're both blaming me and it's unfair.

Should I apologize? but for what. I feel like I'm owed the apology.

Am I being an asshole?