Pectoral Tear, Surgery, and how to keep size

My husband is freaking out.

Last week, he was benching over 300 lbs on a flat bench and tore his pectoral tendon, resulting in emergency surgery that will take place in 3 days. Its been a crappy week.

He has been training for the past 2 months, gained a ton of mass and muscle from his workout, and is completely freaked out that he is going to lose all his hard work by not being able to workout. I kept his diet clean, with lots of protein, healthy carbs and fat, and he followed a program at the gym that made him finally feel pretty awesome. Than boom; a friggin' obstacle that will set him back a number of weeks.

He will be out of the game for at least 6 weeks, with almost 6 months of rehab to follow.  The doctor said once he see's that he is recovered enough for cardio, lower body etc, he will let him know, depending on how well he heals. In the meantime, he plans on training me, so the least I could do is help him maintain. 

I want to help him maintain as much weight as possible during this untimely event.  Currently, he weighs 178, 5'7 and he is pretty much all muscle (and swollen).  I've been reading online that if I keep his healthy calories high, with mostly protein and healthy carbs, meals every 2 hours, I maybe able to save the weight he has.  Once we get clearance for certain exercises, like cardio or lower body, we will start slow.

In your professional opinion, and for the sake of both his and my sanity, do you have any advice if diet will help in this situation? And what sort of cardio can a guy do to maintain mass (step climber/mill?) Also, do you have any advice for the poor guy about pectoral tears and recovery that I could share with him, just to put his mind at ease. Just trying to be a good wife here, and the more info we have the better. Youtube shows a lot of the surgery, but what I need more info on is scarring, pain etc. The forums help, but I am sure you have seen your fair share of this considering this is a common problem with weight lifters. 

Not going to lie, I must say sometimes it better to go lighter and slower than heavy.  Its not worth keeping up with the younger guys... I think he realizes this now, considering the mess we are in.  

Thank you so much for your help! I hope you can answer me... I'm desperate.

Sorry to hear that regarding your husband. Yes its a tough situation and will take time to recover. honestly i would not feel comfortable giving him training advice without being there and or knowing if the physical therapist (which he should be seeing) is recommending. There truly is not any remedy or substitute for weight training. If he can do cardio and other movements to stay active I would suggest him staying on top of it. more than likely he will lose a lot of upper body mass as if those muscles do not get worked they will atrophy. I would suggest following the advice of the physical therapist and or doctor to prevent further injury. In cases with injury there isnt much you can do other than allow them to recover. His muscle memory will help him in the repair and recover phase, which will help him bounce back faster than most.