I can barely function under stress

I've struggled my whole with anxiety, low self-esteem and depression. This week has been high stress (get ready for the pathetic part) because I'm watching our son's dog for 8 days. She's a sweet dog, but very high energy, and has poor impulse control. The first day she attacked a squirrel in our yard and I was an emotional mess for hours, although bottled it up. Today while I was throwing the ball for her she jumped our low back fence when she saw a young man walking his dog. Thankfully, the dogs were fine and as I apologized he said it's no problem. I had to literally drag my son's dog away while apologizing. All I could think of later is how crazy I must have looked/sounded.

I'm saying all this not for advice, but because I feel what's not a big deal for most people is for me. I've had a headache for days, am exhausted, all because I'm hyper-vigilant about making sure a dog doesn't run off or kill small animals, and am training her nearly all day to stop jumping up on me and my husband (who is older than me and loses his balance easily.) Then I feel like an ogre for losing my patience with her. My point is, it's things like this that completely knock me off balance emotionally, and make me feel like a failure.