Counselling can help a great deal. It’s very early days yet so see how you go, but cancer can dredge up all sorts of issues we haven’t really grasped. Including the fact that, even with an early diagnosis and a great prognosis, we’ve just had a brush with something unexpected that could kill. Most of us remain significantly untrained in things that matter (relationships, parenting, death) and it’s quite amazing that we handle many of them pretty well. But talking through deep seated issues with a trained ‘outsider’, allows you to raise things you may never do with a family member or even a friend. As @Zoffiel says, you may have to shop around a bit to get the right person for you, but if the blues persist, it’s a good idea. Best wishes.