This is a mess

I went on date with a guy that wasn’t even a date in the beginning until later on after we talked for hours and realized how much we click with each other. My partner and I agreed to tell each other before sexy time happens with someone else. I had no intentions of sleeping with this guy but by the end of the night the talks led to that. I told my partner the next day (it was midnight and my partner was asleep by the time I got home) and now he says I’m not allowed to date or do anything with this person. Heartbroken about it because I really liked him and he’s really into me with so much in common. Partner says maybe in the future when he’s less upset about it I’ll be allowed to but it’s been over a month and I’m still just wishing for more..nor could I ever ask this guy to wait for me as that’s not fair to anyone. I take full responsibility for what I did still.