Feeling guilty and useless

Hubby was diagnosed last September with stage 4 lung cancer. 

Chemo didn’t work, trial drugs helped with the tumour but side effects nearly killed him now trying immunotherapy which he started 4 weeks ago. 

I had booked my holiday last year before the diagnosis and was going to cancel it but was advised by the consultant and my hubby to go as I had another family member to stay with him while I was away. 

After lots of persuading by family members I went away for the three weeks as planned.

spoke to hubby every day (even though I was on the other side of the world) and was assured by him and Family looking after him that he was fine. 

Came home yesterday and he looks so poorly and much worse than he was, he looks like he’s given up. 

I feel so guilty about going away and feel as though it’s all my fault that he’s deteriorated. 

Don’t know what to do!