This is a crazy personal choice but, I have to say if it was me, I would get a mastectomy. Probably, to be totally honest, go for a double and say F#$& the risk. But, I also am priveledged to live in a country (Canada) where my provincial/federal health care will pay for a complete reconstruction after a mastectomy.
I wish you all the luck and health in the world. My best friend’s mother just finished radiation and chemo, and she is doing very well.