TIFU by giving my wife a facial in front of my step-daughter

Still processing this one since it took place about five hours ago. Me (45M) and my wife (47F) have been married for about 5 years and have a combined family. Most of our kids are half time with us and half time with their other parents. Anyway, my 20yo step-daughter's room is just down the hall from the Master Bedroom. About 6 weeks ago, she started sleep walking and wakes standing in random places, she even woke up in the kennel with our dog once (yes I know it's super strange).

Because my wife and I are trying not to scar the kids, we wait until they are all asleep before we have sexy times. Many times this means we go to sleep and then wake each other up in the middle of the night for sexy time. Last night was one of those nights. When we went to bed (between 8 and 9 because we get up at 4am to workout) kids were still up and milling around, so we figured we'd wait until the middle of the night or have a quicky before we went to the gym.

A few hours later I wake to a stiffy pressed up against my wife's backside and decide it's game time. Within a couple of minutes we are deeply into it and a few minutes later we know it's about time for the grand finale. My wife breathlessly tells me the words that every man around the planet loves to hear "I want to finish you with my mouth". I practically jumped off the bed and stand there as my wife gets on her knees to give me a toe curling BJ.

I am going to interrupt this story for a moment to give another little factoid. My wife was a single mom to four girls for many years prior to meeting and then marrying me. Her and her daughters are pretty immodest around the house. I'm constantly asking them to put shorts or sweats on.

Anyway, there I am standing naked beside my bed. My wife is on her knees sucking my soul out through my dick. My eyes are closed my head is back and I'm just about to release when I get that weird feeling that I'm being watched. I open my eyes and see my 20yo step daughter standing three feet behind her mom in a tank top and panties. I reflexively pulled back from my wife's mouth which caused her to grab extra hard the next thing I know I'm spraying my load all over her face while I'm looking directly into my step-daughter's eyes. My wife is trying to be playful and thinks I'm just feeling kinky and I was just trying to cover myself. My step-daughter just stands there for what seemed like an eternity before saying "holy shit" over and over and walking out of our room and back to hers. Of course as soon as my wife heard her daughter's voice she became much less playful and everything got deadly serious.

So now I've gone to the gym, am sitting at my desk working and my wife has been in talking with her daughter for the past couple of hours. Honestly my only fuckup was the timing. But it did happen today, so there is that.

TL;DR My wife and I had middle of the night sexy time, sleep walking step-daughter walked into the room and watched me frost my wife like a cake.

Follow Up: They are done talking came out of the room laughing and stuff so I guess no harm no foul. My wife said the three of us should sit down later and talk about the what happened and that her daughter has some questions.

Edit: To all those wondering why I added the part about how my step-daughters dress. At the time I was worried that my wife was going to be thinking I was a freak for nutting as soon as I saw her daughter in her panties. That didn't happen at all, when I mentioned it to my wife she waved it off. If I were to write this post now I would leave it out, but it was important to my mindset at the time.

Edit: People are claiming that it's been deleted, but I still see it and haven't tried to delete it. Any how, I just tagged it as NSFW (something I should have done in the beginning, but I didn't know) maybe that fixes things. I'm enjoying some of you funny sick people.

Edit: Well we just had an hour plus conversation. My step-daughter was just wanting to clear the air (she was a lot more mature about it than I thought she would be). She asked a couple of questions about how often is normal and stuff like that. I don't want to get too specific, but all of her questions centered around how far my wife and I pushed each other's boundaries sexually. We were open and honest with her about it. Turns out she is not a virgin (I am actually surprised) and the first guy she was with was very pushy. The guy she's with now is very laid back, but maybe too laid back. We told her to be vocal with him about what she wants. I think she understands, but my wife is going to follow up on the conversation later.

BTW, she did not even realize what was going on at first. All she saw was that I was standing there naked. It was when I saw her and started to freak out that she understood what was going on.. My wife and I have already stripped the bed and are washing the sheets and comforter. I am shampooing the carpet this afternoon and there are spots on the wall that need to be washed. My wife found some of my material in her hair... at work she sent me this pic.

I got back on here and this post is at almost 10k and my inbox is screaming for mercy. I'll try to answer as many questions as possible.

OK, I'm disabling inbox replies. I can't believe that my (by far) most upvoted post is about my wife and I nearly emotionally scaring my step-daughter. Be well everybody.