I might be all-mixed up here, but I think
@FauxLiz 's original upset had been over her T offering her a day she couldn't usually do- but can juggle her schedule to accomodate. Then she got angry and reacted verbally in an e-mail.
But, she had been the one to cancel in the first place..
Then she said she's dealing with self-harming, and has been open with her T about it. And hence is struggling, also, to give up the 'tool' she uses.
And her T hasn't responded, and she's trying not to mind-read.
My 2 cents isn't important, though I got over some years of self-harm, and I have SI.
If I had to guess, I'd say out came a reaction, possibly fueled by thoughts of giving up tool, or being triggered, or expectation, or hungry-angry-lonely-tired etc, grief, etc.. Your T sounds like, as others are suggesting you do, making it a priority to try to help you, and you making time helps yourself.
I don't think you mentioned your T demanded you give the tool up on the spot; when you do & as you make changes a plan will increase your safety and success.
Yes, I think you need (and might want) to make an apology. It sounds like your T is kind, probably used to many people over-reacting, but still not obligated to minimize your reaction, or even not feel badly (they are human too and have accomodated you past- eg early a.m. appt's- so that maybe they would hope you remember they have, I think it's appropriate to be thankful for that as well, though I realize you are paying).
Not sure if that's helpful. :confused: