If you sleep with someone else 1 day after breaking up, is that also cheating?

So my boyfriend cheated, I broke up and blocked him. I didn't listen to his excuses nor his requests for a 2nd chance.

The following day (exactly 24 hours after the break-up), I slept with my former supervisor. Is that also cheating or not?

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I didn't give any time to mourn for him. The thing is I don't regret it at all.
If you sleep with someone else 1 day after breaking up, is that also cheating?
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