Granite, it sounds like your T is probably concerned about your health, and probably was just trying to reassure you that you don't have to come if it is going to cause more stress (and possibly more health problems).

I think when you hear anger from your T (remember how she has told you multiple times that she has never been angry with you? This is one of those times as well), you confuse her being upset FOR YOU, versus her being upset AT you. She probably is adamant about you not contacting your mother, because it will only hurt you--and you especially don't need that going into a major surgery.

i honestly think she is angry at how much stress and your traumatic upbringing has affected your health--a triple bypass surgery is very serious! Could you sleep on it tonight, think about it tomorrow, and if you are really feeling that she was angry, leave her a message asking if she was, and could she please call you back because you are worried about it.