I’m sorry that you have found yourself on this forum @bless2025. It’s a club none of us want to join.
I was diagnosed with invasive ductal carcinoma 11 months ago and like you I am HER2 positive. I lurked on the forum for a month before posting on the HER2 thread. If you’ve not found it already, it is really worth a read. It took me 4 hours from start to finish. I reckon that may have doubled by now! The fabulous group of supportive women scooped me up in my low moments and gave me hope with their shared stories of getting through treatment. There’s lots of sage advice, kindness and humour alongside the reality of how crap it is.
I found it hardest at the beginning. Telling my children. Sharing the news with family, friends and colleagues. I catastrophised. I was scared. The uncertainty, lack of control, investigations, drip feeding of information at each appointment as results came in and then waiting to start treatment. Once I had a plan I felt so much better. Then it was head down and get on with it. It felt insurmountable at the beginning but it’s doable. I had chemo and targeted therapy from January till May then a double mastectomy with immediate reconstruction in June (I had ‘it’ in both 
). My targeted therapy finishes in February and I’ve hormone blockers for 5 years as mine is oestrogen positive too.
My life has changed and I have changed but I look back and marvel at what my body has got me through. It’s been a lot but it’s not been as awful as I thought it might be. You will get through it too. You will have all of us on your side.
Here’s the link for the HER2 thread. X