It happens,we all make mistakes,like she says.
I have done this also twice actually,came in before using a substance and it didn't really kick in until mid session and I started acting wonking. T realized and I confessed that I was a little high. The other time she already knew and was upset with me. Told me not to come back like that again,and it wasn't acceptable. I understand why you did it. I'm sure you feel embarrassed (well I did) but it happens.
Honestly,if you apologized,there is nothing more you can do at this point. If you feel the need,just explain to her what was happening before you came to see her.
I'm sure she understands and I'm sure you're not the 1st client that has done that.