Caught Off Guard in My Friend's Bed

I’m a trans woman in my early 30s. I’ve been okay with being single for the most part; it gives me space to focus on myself, and I haven’t felt much pressure to date or be in a relationship lately. Recently though, something happened that has left me feeling confused and somewhat troubled. A close friend of mine, let's call him Alex, who’s in his mid-30s too, is married with two kids. He knows I’m single but insists we aren’t looking for anything more than friendship. We’ve grown closer over the past year or so, talking about everything and nothing. I find myself confiding in him a lot, some might say I rely on him too much. One evening last week, we were both at his place because our other friend was throwing a party nearby but neither of us wanted to go. We had drinks and played some games until it got late. Alex mentioned he needed to get up early for work the next day, so I figured I should head home too. But then something unexpected happened, I don’t know if it was because we both felt comfortable around each other or what exactly, but there was this moment of intimacy that wasn’t planned at all. We ended up spending more time together in a way neither of us had anticipated. The morning after, I woke up alone and feeling conflicted. Alex had left for work without waking me, but his wife was calling him, asking about why he was home late. It felt like something happened between us that shouldn’t have, something both thrilling and scary at the same time. Now days later, I’m still not sure what to make of it. Did we cross a line? Should I tell Alex how I feel or leave things as they are? This whole situation has made me realize there’s this complicated mix of feelings bubbling up inside me whenever I think about him. It’s strange because I thought I was doing fine being single, but now that uncertainty is back. I’m not sure if this counts as a mistake or just a momentary lapse in judgement, either way, it’s stuck with me ever since.