It’s really tough to face, and a big shock, but recovery is very possible and there’s probably never been a time when more is known about how to treat cancer. Good advice from all above - one step at a time, each case is individual, chemo can be manageable (I continued working with no difficulty throughout treatment) and talking things through with a complete stranger trained in cancer counselling can be immensely helpful.
One of the risks of losing lymph nodes is lymphoedema so best to state it up front. Do not google this! As my therapist says, full of third world, 30 year old images! It can be worth getting a referral to a lymphoedema therapist, having occasional checks even if you do not observe any change. Early treatment, as with most things, has great benefits. Should lymphoedema occur, exercise (a few minutes every day), a well fitted compression sleeve and massage can work well. I’m over ten years post diagnosis, my arm is fine (normal lifting, working, no pain or discomfort) with simple care and about the only thing I shouldn’t/can’t do is soak it in a hot spa!! I’m the one soaking happily with one arm out of the water!
Best wishes, it’s not what you planned but you can still have great things in life ahead of you, look at this as just one of the inevitable bumps in the road.