Okay, it's a long one so bare with me if I trail off in parts.
I have been with my boyfriend for just over a year. He is not the father to my two children (age 6 and 2), but we all live together, they adore him and he loves them like his own (I assume, he doesn't actually have any of his own yet!) and I am very happy with him. Even though I am happy, there have been numerous occasions in the last year where I have tried to call it off. I think I am worried about him cheating (which is super hypocritical of me considering what I'm about to say!!) Because my children's dad had numerous affairs, was very abusive and eventually went on to leave me and the kids in Dec 2018 for a girl 8 nearly 9 years younger than me (I was 25 at the time). I guess I am just a paranoid mess, and that's basically it. Anyway, since lockdown hit work has been really fucking hard. So my manager suggested we all go out to have a drink and just let our hair down. We did this on Saturday night. In our office there is 3 women including me, and the rest are men. It is a very male based job. We were all having a good time, I don't often drink, in fact the last time I touched a drop was last September, so pretty quickly into the shot flowing I was slurry word drunk. But I still had a handle on what I was doing. I went outside to vape at one point during the evening, a colleague followed me just to make sure I was okay. We talked for a minute and then he left. Shortly after my manager came out. He came over and asked again if I was okay, I said I was, we awkwardly chatted for a few minutes and then he said "can I share something with you" I said yes, and then he said nothing for a minute, he got closer and before I knew what I was happening we were kissing. Not your average peck on the cheek, full on snogging, at one point I'm fairly certain he had a quick grope too. Anyway, it stopped promptly after another collegeue came out and saw us. My manager left and I had no idea what to do. I pulled another coworker outside to have a chat and suddenly before I knew it I was telling him what we'd done and how awful I felt and that I felt sick to my stomach and blah blah. He was so calming about it and very nice, told me these things happen and it's probably because I don't normally go out or drink that it's happened. I agreed and then went back to the bar. Later on, when I was at the bar my manager came up to me and said "I wanted to share and say, if things were different we would 100% be together." What?! Where the fuck did that come from?! I have been working with this man for over a year and have never had anything more than emails from him telling me I'm doing this wrong or that blah blah blah and suddenly he's coming out with that. all I could muster up was saying back "I have two kids" I think, because I knew he didn't like kids. He replied with "I would house you and them and love them". Then he kissed me again and that was it. After that all night he got oddly protective of me, every time I went to talk to someone else he'd joke and come over and say "No she's mine!!!" My partner picked me up when the night was over and my manager went over to the driver window to talk to him, he didn't say much other than I was a "good girl" 
and then left us to it. I was so hungover the next day and he messaged me asking if he could meet me at my office (I'm a lone worker in one of our 7 offices) after work today. I agreed thinking he wanted to clear the air. I have to admit I was nervous the whole day today, thinking he might try it on again, or thinking he would say he didn't mean it (I don't know if I secretly wanted him to mean it, which is confusing me) anyway, 5pm rolls around and I get a message saying "Don't wait around for me, I'll catch up with you tomorrow. Just wanted to check you were okay nothing more nothing less". What the hell does that mean?! Now I feel so sick to go into work tomorrow as I am working out of his office in the morning and it'll be just us there for about an hour. I don't know if I have a question, I think I need someone to tell me to grow up and stop being such a dickhead. My partner is so good and so lovely and loves us all so much and does every thing for us, so why the fuck am I worried about my manager all of a sudden!? I have honestly never thought of him in this way until now and now I can't stop thinking about him. To make it worse I'm worried sick the colleague who saw us is going to tell other people about it and I'm going to be labelled the girl who kisses the boss on a night out 🤦