I accidentally had with my sister while we were sleeping?

My sisters bf recently dumped her and now she has no place to live.I allowed her to stay at my place but i only have one bed so we have to share it.I could have let her use my old sleeping bag i used to screw in when i was a hippy but thats not how i treat family.Anyways one night we were sleeping and we were both on our sides.I woke up and felt this warm wet feeling on my so i looked down and saw my morning wood poked out of my boxers and was now rubbing against my sisters .I was so horny i wasnt thinking so i started to push it in.My sister moaned about overpriced potaoes or something like that but she didnt notice i had my in her so i continued moving.Eventually i pulled out and shot a load all over her .I quickly wiped up and deposited the tissues in the bathroom.When i came back my sister was awake and gave me a long cold stare but she quickly went back to bed.Do you think she knew i banged her in her sleep?How should i deal with the coming awkward days?