Is it cheating if you're not official

​

I (28 M) have been seeing someone (29 F) for 3 months.

I felt the relationship was going well and really liked the girl, I offficially asked her to be my gf 3 weeks ago which she declined. She explained she has a lot going on right now to figure out and can't currently commit but is happy to keep seeing me.

I took that on the chin and accepted that was fine at the time, but now I feel very much in a limbo state and have semi come to the conclusion if she doesn't know if shes ready to commit to me at this stage it's a bad sign.

Since then I've been away on a trip abroad, I got very drunk and had a one night stand with a girl I just met and have no feelings for or interest in pursuing. I feel really bad about this and not really sure what the next course of action is.

Have I cheated and is it worth telling the girl I'm seeing about this?