You are an intelligent and caring person who will succeed at whatever you set out to do. Don't let that bad experience make you think you are not effective or successful. Some days are good and some days are great, and some days are not so wonderful. Focus on the positives. Try to get better each day. Learn something each day from the previous day and make improvements. Keep writing in your journal and your blog. Reflect out loud.
You are teaching skills. "This is how to..." NOT "This is what..." Focus on ways to explain skills. Practice think-aloud skills at home this summer. Rehearse your lessons before you teach them. You are new. You are not going to be able to wing it and be effective. Try out different styles and ideas.
This is going to take time. And it is going to take a lot of hard work. Nothing worth doing is easy, and this is one of the hardest things you've ever had to do - being The Little Man's mom is the hardest thing - but this is a close second. Remember how useless and terrible a mother you felt like when he first came home? You cried all the time. You felt like it was going terribly and you would never, never get the hang of being a mom. And you didn't have the luxury of being able to quit. The Little Man was there. Every day. And every day you had to get up and keep trying. Learn from the day before and move on. And LOOK AT YOU NOW! You love being a mom. You have great ideas and share them with other moms. (Just this week you shared ideas for getting a 2 year-old to brush his teeth! Dinosaur roars and letting him brush your teeth too.)
Just keep going. Keep at it, and do the best you can! Have a growth mindset... you can learn what you need to learn, and you can ask questions of other people who know what you need to know.
And stop sitting in your classroom alone! Go to other rooms and watch other teachers. Go to the lunch room and talk with the other teachers. You can't be so shy all the time. Suck it up and just go.