Breathless

I recently found out that my mum has stage 2 cancer and she's going for chemotherapy . I am currently studying overseas and it is really hard being away from her . Last night while thinking of her I found myself breathless , suffocating to be exact . Despite the window being wide open I was struggling to breathe . I do not think I am coping well with the news . How can I support her when I can't even hold myself together ? What helps ?