Need help from you Sagittarius

I hope you have time to read into this. I tried to shorten it best I could. I.m in an odd predicament. I feel I'm being framed and need a Sagittarius perspective on this. And what I should do.

I have a Virgo friend (female) who is in love with this Leo. They dated a few years back and from what I've heard he broke up with her because his high school sweet heart, a Sagittarius came back in town. They remained friends and my Virgo friend befriended the Sagittarius and keeps saying to her ,and everyone that she has a "brotherly love" for the Leo. When she found out that Sagittarius got pregnant she has been up in the middle of them saying how she's more excited about them having a kid than they are. It took a while but Sagittarius finally "trusted" them together. Fast forward to this past new years. I got invited to go camping with Virgo so I went , there was supposed to be more people but everyone canceled , it ended up just me, Virgo and the Leo, the sag refused to go. I went to bed early and about an hour later I got up to pee and they were having sex. They weren't even quiet or sneaky about it. I'm like woa OK this sucks because now I know this and I didn't want too be in middle. Virgo asked me to just ignore and not tell anyone. I agreed and said it was between her and leo. Well few days after our whole group of friends do a late "secret Santa" and guess who was my secret Santa? The Sagittarius. I'm not the kind of person to say something but I probably looked like I knew something. I actually got mad at Virgo and Leo because they were so obvious. They were playing cards and making jokes like how the game was like camping "intense" . I didn't laugh but neither did Sagittarius. I felt bad for Sagittarius . I recently ended up in same job as the sag we haven't worked together a lot because she just had the baby.

What's bothering me is Virgo begged for me to hang out with her yesterday so I went. We bought perfume and stuff. Then she asked what my favorite scent was. We joked about it and shopped around. She then asked if I'd seen baby I said yea on Facebook and she insisted we go see them at 8 pm . I went and Sagittarius kind of ignored me. She asked if I wanted to hold baby and I did but that was extent of our Conversation. Virgo then tells leo "so she smells good right? Vanilla is her favorite scent." Then leo said "oh thats what you were talking about" apparently she was texting leo whole time we were shopping. Sag got confused and looked at me funny saying what's that about. I said we were shopping earlier. She then only talked to Virgo and Leo. Then today leo sag and a friend of theirs visited work. I said hi and sag said "you seem nervous" . I was stressed from work but no more than I usually am. She then ignored my existence, the leo kept talking all nice saying hi and called my name. I was polite but no more than I usually am.

But it occurred to me that I know she knows hes screwing around but I think both Virgo and Leo are trying to cover up and possibly put it on me. What do you guys think? Do you think Sag knows its Virgo or thinks I'm at fault. I only ask because she seems distant from me. I really feel for her and she's super sweet. I've been friends with Virgo for longer so I want to be good friend but I also like the sag and don't know what's best course of action