Bowel cancer scare anxiety

Hi I wonder if anyone could give me some positivity. 
I am so worried my partner has bowel cancer he is 58 and we have two young children. 
He lost 4 kg since January and was feeling tired and dizzy so I made him go to the Gp. It came back low side of normal iron and gave him tablets they asked him to do a fit test I was so sorry we bought a home test and it was positive . My anxiety is through the roof all I think of is that he is going to leave me