That's all you can ask of yourself. If you did your best and things just didn't work out, you don't owe an apology to anyone.
And you certainly don't need to feel 'bad' about it -- or, worse yet, guilty.
Every true emotion has a counter-balance, an opposite. There isn't one for guilt. Guilt is a man-made concept ... made for control.
What we need to replace that manipulative concept is simply "responsibility". NO GUILT-Tripping' there ... ;-) ... just a better end result!!!
That's all you ever have to give. All the rest is image and competition.
Every misstep is a step to higher truth. Be proud.
We all make mistakes. Although the world is full of suffering, it is also full of the overcoming of it.
Your willingness to wrestle with your demons will cause your angels to sing. Use the pain as fuel, as a reminder of your strength.