Hi there,
I can understand why you feel as you do and you are allowed to express those feelings. Its understandable to feel disappointed and angry.
I think we often see our therapists as those who should always be there when we need them but sadly they get sick or have to have time off ( my T has been off for 5 months due to health reasons and it has been really hard). I am sure your T would have felt bad about having to cancel on you and as someone else said...perhaps she was trying her best to get through the day and was just feeling so unwell that she felt she couldn't go on.
If she had of gone on to see you, you may have found she wasn't able to focus on you during the session as she felt unwell and that too could have left you feeling she didn't care about you. You may have found you caught the illness/bug etc from her meaning you would end up missing a session anyway. Perhaps if your counsellor hadn't stopped and went home when she did, she could have made herself worse, having to take even longer off work....so although its really hard, perhaps her decision was the best one....even though it really doesn't feel that way. If you think back to times T has helped you....would you want her to be suffering or can you try and help her by understanding why she may have done what she has? It may help you feel better too.
I hope you get to see her again really soon