First, let's challenge the initial belief. Who decided that to have happiness we have to have things or certain circumstances? Did you ever stop to think about the tribes living New Guinea? Think you they aren't happy? Indeed, they may be more happy to be living such a simple life!
Barring that, lets say you did achieve those goals, only to watch them crumble around you. Many say that is failure: their marriage failed, the business failed, etc. I'm fond of a joke by a famous comedian where he talks about people "awwwing" over his divorce and he says "Don't "awww" that! No GOOD marriage has ever ended in divorce!!" Congratulations are in order, you are doing something to take care of yourself!! You tried something, it didn't serve one or probably both of you, And if you are bemoaning your kids living in a split household: First, that household likely wasn't happy or healthy, so you are making a better choice for them. Second, now there is possibility for them to be surrounded by even more love with more family! It teaches resiliency, a key attribute. In fact, possibly the ONLY necessary attribute for navigating life because the only thing you CAN count on is change.
You didn't fail, you certainly aren't a failure. YOU tried, you just found one thing that didn't work. In this vast VAST world of opportunity, you've only begun to explore. And you, are still you. Amid those broken dreams, lives a bright shining soul that can chose happiness, even when you feel lack, because you still have the chance to experience, ALL of it, even the bad stuff. Because from the mud rises the lotus.