Barbara - it is ok to feel sad & it is ok to cry.
There should be no guilt or shame with that - you did nothing wrong!
This battle against the big C is as much of a emotional, spiritual one as it is physical. Stay strong, positive and vigilant and do not feel ashamed to ask for help.
Prayers are with you during the next few weeks of treatment and wishing you all the best

Kindest Regards,
Jay