Advice about mastectomy

I’m reeling at the moment and would like advice on what questions I need to ask.

I was originally diagnosed with invasive ductal breast cancer in Oct 2015 - Grade 3 aggressive and fast growing 8.5cmx6.5cm. I had 8 cycles of chemo, which shrunk it and went for the option of therapeutic mammoplasty in July 2016, followed by radiotherapy. I had another op on the other breast in July 2017 to remove ADH cells and reduce to match my other breast. More cosmetic surgery in July 2018. I found a lump in the original in Dec 2019. Everything pointed to fat necrosis - nothing on mammogram or ultrasound that suggested cancer, the biopsy was inconclusive but didn’t show anything cancerous. I had an excision biopsy in Feb 2019 as due to my history to be on the safe side. Saw surgeon for the results on Monday - he said my original cancer had returned (didn’t know the grade) and I had to have a mastectomy as I couldn’t have radiotherapy to that area again. He said we could talk about reconstruction “when the dust had settled”. He has requested CT and bone scans to check for any spread. Op to be within 4 weeks after scan results in. I really didn’t see it coming as they had kept saying nothing to worry about. I realise now that I have a shed load of uncertainty (as well as all the other emotions!). The cancer is ER+ve as it was last time - I’ve been on tamoxifen for the 2.5 years between original surgery and finding the lump......just been told to stop taking it ready for surgery.

I am ringing the breast care nurse this morning to ask to meet with someone - my questions so far are:

exactly why do I need a mastectomy?

what is actually there that needs removing now?

is there another option - ie monitoring and/or other treatment? 

what are the risks if I don’t have a mastectomy?

What mastectomy options are available eg reconstruction at the time of mastectomy and why this hasn’t been discussed/offered; if not possible what type of reconstruction is likely to be the best option for me and in what timeframe?

My question is are there other questions I need to be asking as my brain is a bit in freefall - I really hadn’t expected to be in this position again, and certainly not so soon.

Any advice is greatly appreciated, thank you

Judy