My roommate's boyfriend kissed me while she wasn't home. I don't know what to do. help!! ?

Anonymous
even though my university classes ended a few weeks ago, I'm still living in the same area.

yesterday my roommate went to work to earn some more money to pay for her half of rent. i had the day off of work so i was just chilling and cleaning. she was working from 10:00am till 9:30pm.

at about 9:00pm her boyfriend stopped by asking if she was home and i said "no sorry (his name), she's working for another 30 minutes". he said "well can i at least come in and just wait till she's done if that's fine with you?". i said "yah, sure" and let him in. about 10 minutes of him being in our apartment silently sitting in a chair, he walked over and came behind me while i was washing the dishes, and kissed me on the lips.

i pushed him away milliseconds after and said "uhm dude, what the hell are you doing?" in a shocked voice. he said "kissing you, what does it look like?". i told him "well don't. you obviously have a girlfriend and it ain't me". and then i continued to tell him to quit and back off cuz i honestly thought he was drunk or high or whatever.

about 15 - 20 minutes later, my roommate came back in from work. she walked up to her boyfriend, kissed him on the cheek, and they went out to wherever they were going. i could tell that as soon as she walked in our apartment, she could sense that something wasn't right, which something wasn't cuz she looked confused and said "uh gabbie (my name) why do you look like you just seen a ghost?". i said "oh uhh, it's nothing" in a hesitant voice, then went to my room and they left.

so what do i do? I'm going insane knowing that her boyfriend tried to get with me. plus, it's not like they've only been dating for a year or two. they've been dating for 5 years, almost 6. i want to tell her before i crack completely, but i don't want to cuz i don't want her thinking i tried to have this make out session with her boyfriend cuz thats not what happened. i don't want to ruin their relationship. but i can't stand knowing that this happened. please help me!!
My roommate's boyfriend kissed me while she wasn't home. I don't know what to do. help!! ?
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