The things about which you inquire are not just associated with startups, they are also associated with life in general.
For me, it depends on the importance of the outcome. What was the breach? Was it a deal breaker? When I had my house built and was experiencing all the trials and tribulations, it was thoroughly stressful but has been let go. I "fixed" the stresses the best I could and got over it. When my job was eliminated, I found another and got over it. When my daughter I was supposed to adopt was instead, after 2+ years, reunited with a birth parent by court order, I was devastated and to date, remain heartbroken, but I`ve still gotten on with life.
You cope. You figure out a better way to solve the situation if it occurs again, file the new solution in the back of your mind, and move on to the next situation. Learn from it. That`s life. And I do believe Universe (God) has a plan and we are here to figure it out!
Jillybeans