As a mom of four (ages 11 to 16) and a special education teacher I understand how patience can run thin. I take time for myself. Even a 10 minute walk during plan time can refresh and replenish the patience. When I walk at home, I usually have at least one child with me. It gives us "special one-one time" that is hard to come by. If there is an "issue" going on, it gives us time to talk about it.
Sometimes, taking a much needed day of rest helps a lot. Have lunch with friends, go shopping, or just go to a quiet place by yourself. Read a book, watch a sunset, ride your bike, take a drive in the country...find something to bring you peace and serenity, if only for a little while.
I find I'm a better mom and teacher after! I hope this helps.