Is it normal to have lesbian fantasies while you're married?

4 years ago, my husband and I were partying with some friends. We were the only ones with our own house pretty much other than my boss who came out with us too. The plan was for everyone to sleep over since everyone was intoxicated. My husband went upstairs for the night and I stayed downstairs with my boss. She's older than me but so freaking hot. I've always known I'm also attracted to girls and my husband is aware as well.
Anyway, that night let's just say things got a little steamy. I started sacking on my boss' luscious tits. Then I worked my hand between her legs and started feeling on her moistness. She told me to stop, to think about my husband. But I didn't care. I was horny & was determined to give her oral sex. I knew she wanted it. I pleasured her until she reached her peak.
At work things were weird at first and I even thought I didn't like girls after that. Thankfully, we're both straight forward and professional at work so we dropped it and moved on. We remained friends.
We no longer work together however lately we've been setting if you will. Lol. I just wanna tasee her again so bad. She turns me on. Don't get me wrong I love my husband and our sex is amazing, but somehow the thought of my old friend sitting on my face turns me on so much. I tried telling my husband how I've been feeling more lesbian than usual lately and he knows about what happened for years ago. He wasn't happy and considers it cheating but him and I are soul mates. I'm just being selfish and horny but I can't help it. I have a feeling my old boss and I will be getting naughty soon and I don't feel bad. Help!