I (33M) hooked up with a friend’s friend (33F), crossed a line with her mutual friend, and now she’s distant. How do I repair this?

TL;DR: I hooked up with my friend’s friend (Megan) a few months ago. She acted distant, then started texting me frequently and we hooked up again before she left town for a month. While she was away, we texted every day and made plans to meet. On a vacation with mutual friends, I crossed a line by putting my arm around her friend (Sarah) while we were sitting on the back porch at 1 a.m. with a lot of beer involved. When Sarah asked about Megan, I said things with Megan are confusing and seem platonic. This was a defense mechanism, because Megan has made it clear she doesn’t really want people to know. I pulled my arm off Sarah quickly and told her I’m not this guy. Megan now seems distant, and I think Sarah told her. I regret my actions and don’t know how to move forward.

A couple of months ago, I hooked up with Megan (a friend of a friend). After that, she didn’t show much interest in me. But eventually she started sending me random texts. About a month ago, I met up with Megan, Maria, and a few of their mutual friends. Megan asked me if she could kiss me. That day we were making out when Maria wasn’t looking because Megan didn’t want her to know. We hooked up again that night before she left town for a month.

While Megan was away, we started texting walls of messages every day and made plans to meet up once she got back.

During that time, I went on vacation with our mutual friend Maria, her husband, and another friend, Sarah. Both Maria and Sarah asked me what was going on with Megan. I brushed it off and said I didn’t want to talk about it, since Megan had made it clear she didn’t want Maria to know details.

Later that night, Sarah and I were on the back porch at 1 a.m. I had a moment of bad judgment (and too much beer) and put my arm around her. She asked again what was going on with Megan, and I said I wasn’t sure, that it seemed kind of platonic. Looking back, I realize I said that as a defense mechanism because I didn’t want to reveal anything Megan wanted private. I honestly don’t know why I also put my arm around Sarah. I quickly pulled away and said, “I’m not this guy.” Sarah got upset and went to bed. She told me she didn’t want to murky the waters with Megan since they’re friends.

Now I believe Sarah has told Megan everything. Megan’s texts have gotten shorter, and it feels like she’s pulling away.

I know I messed up and wish I could take it back. Nothing physical happened beyond me putting my arm around Sarah, but it still crossed a line.

My ask: How can I take responsibility, communicate honestly with Megan, and try to repair this situation?