Sounds like you have some wonderful support. I was certainly not trying to influence your decision but just reassure you that if you do end up having a mastectomy it can be ok.
As you say it will really depend on the issue of possible effects from radio. Viv is right when she says this can be different for different situations. In my case even though I had a mastectomy I still had to have radio after chemo. They were unable to completely avoid my heart and lungs because of my situation so I totally understand your concerns.
With your own research and that of your daughter's as well you will be very prepared to ask all the questions of your medical team. This will give you peace of mind about your decision. Meanwhile reading other people's stories on here may help prepare you for what is ahead.
It does get better once you have your plan. Hope you hear from your cardiologist soon. Deanne xxx