Hi Reny, my husband was diagnosed when he was 39. He was usually the youngest patient in the chemo ward by several decades too(but not always.)
His moods seemed fairly stable throughout- he's never been a particularly moody person. I think he was able to express as much of himself as he needed to, although he is English, and was bought up with a 'stiff upper lip' etc, so it wouldn't have been easy. He was very practical and resolute throughout.
He is now 2 years post treatment, so it seems for the moment like that part of our lives is over. He is really busy just living- he's just started a new job, has developed some new hobbies and is just getting on with things. Unfortunately his cancer was diagnosed in the context of a couple of years worth of really severe job stress, culminating in redundancy earlier this year, so I think he's coped remarkably well with all the s*** he's had to go through.
Maybe you just need to give your husband time. He will react to this the same way he's reacted to bad stuff in the past, so unless he isn't following his usual pattern I wouldn't worry unduly. Take care of yourself, too. It's definitely true that cancer effects the whole family- I used to feel like 'we' had cancer, it just happened to be in my husband's body.
Take care and keep in touch, love Emily