Urgent breast appointment today and terrified

Hi guys 

I found a lump in my left breast a couple weeks ago and went to see GP last week. The GP said she is fairly certain its just tissue but referred me to the breast clinic anyway. I have my appointment this afternoon and im absolutely terrified. I am 39. I have two adult children and a 6 yea r old little boy. I cant bare the thought of leaving them. 

I cant eat, sleep or think straight. I suffer with anxiety and my head is spiralling!