Has anyone else experienced this?

Yes.

This might get long-winded. I should note that, I too have a family and the first digit of my age is a 4. Allow me to tell a story...

Around WWDC 2014, I started working on a game for iOS. I wrote it in Swift, at a time when the language was still in beta (i.e., Xcode 6 Beta 1; you couldn't deploy Swift apps to the App Store at that time).

Even though the game was essentially an 80s-inspired space shooter, I became singularly-focused. I just knew that this was going to be my "make or break" moment. I pounded through all of the struggles of working with a language that was still being developed.

It was rough. I'd never even owned an Apple product before, so everything was foreign to me. I'd retire to bed at a reasonable hour, but be "eyes wide open" at 2:00am or 3:00am, literally waking up from a dream that's an answer to a problem in the code. The urgency kicks in... I'd try to fall back asleep, but it was always futile, so I'd throw myself in the shower, get dressed and light the fuse.

This feeling was exacerbated near launch, because you're literally a few hundred meters from the summit, but you're exhausted, delirious, hungry, thirsty, sleep-deprived, and everything else. The wind and the cold is cutting through your gear, making it feel as if you are wearing nothing but your small-clothes. Your visor is completely frozen over, and nightfall is looming, but you still have to summon everything from within you to bring it, because there is no one who can bring it but you. No one is going to summit for you. No one is going to slide their stacks "all in" but you.

Even the people around you won't understand the mental suffering that you are silently muscling through; you, torn between two worlds as you push and strain to your personal limits. You measure the day's progress in centimeters rather than meters. You will either summit, or freeze to death on the mountain in your boots; the summit in sight, but just out of reach. Which-ever event happens, you feel alone, either way, because no one is carrying the sheer weight of The Vision than you. It is all you. It has only ever been you. There is no one to save you.

It turned out that there were too many days of this... and it was my "break" moment: I ended up in the hospital in the winter of 2014, physically exhausted. Completely spent. I recovered after 4 days of IV.

I went on to launch the game in early 2015. It didn't launch me into super-stardom like I had believed that it would, but I did finish and I learned an incredible amount about game development... and, as it turns out, about life and myself, which included a number of things, but two of them in particular might help you at this time:

1. Balance - Everything must be balanced. The Middle Way, if you will. This is absolutely vital. Work on your projects for the sake of working on them, not to drive yourself to some goal, because in reality, you have little to no control over what will result. So, learn to love the process. Also, live in balance by bringing exercise into your life, eating right, meditating, etc.

2. Comparison - Comparison must be silenced. It is truly a source of suffering. There is great danger even in seemingly harmless comparisons, such as, "I'm in my 40s, and I haven't achieved X, Y and Z." This is quite harmful to personal growth and production. The reality is that comparison is the ultimate puzzle: it has no solution. That is to say, it will never end. The mind will always set up more to achieve, more to do, more to conquer. And then, even when you have achieved, the mind will say, "Well, what's next? So and so has done Y... sure, you did X, but what about Y? You haven't done that." We can carry these weights of comparison to the bitter end, and let them drag us down like a stone into an icy, freezing river, where we will drown to death in our own self-pity and sorrow. Alternatively, we can free ourselves by deciding to care only about what is important for us, and on how we can bring our light into the world. This will allow us to break the chains that we have allowed to bind us. This is our choice, and it is up to us.

I hope this helps you. I wish you every success. Evolving yourself is a never-ending process. Be gentle with yourself. Set your goals, go for them, but live in Balance.

I leave you with this quote, which speaks powerfully to me:

"To be a warrior is not a simple matter of wishing to be one. It is rather an endless struggle that will go on to the very last moment of our lives. Nobody is born a warrior, in exactly the same way that nobody is born an average man. We make ourselves into one or the other." - Carlos Castaneda