Oh gosh yes Tassie Grandma! I wrote the same thing here a few months ago when I was having chemo and I recall several agreeing with me. I had to have a re-excision for margins too. We're in an unlucky 12%... It knocked me for six as well. My re-excision unearthed a 4cm dogleg of DCIS which had been completely invisible on the mammograms and ultrasounds I'd had to that point. So probably a good thing in a weird kind of way.
Take some deep slow breaths to settle your nervous system. Distract yourself doing things you enjoy, seeing friends, giving yourself a treat, and try not to cross bridges until you come to them. Hang in there fellow warrior. Big hug, K xox