Tricia Klein said she couldn’t believe how considerate Timothy’s classmate, Carter, and his mom, Ainsley, had been.

Timothy, 7, was diagnosed with non-verbal autism when he was 2 years old. She says her son gets anxious in social gatherings, so they have turned down countless invitations over the years.

I would hate to take the spotlight from the birthday child," wrote Klein in a blog post. "We parents of the 'specials' know only too well the hurts our kids feel when they are left out of the social gatherings relative to childhood."

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But last year, she received a very touching invitation from Ainsley to Carter’s birthday party.

“I was shocked that someone would take the time to write the note and be considerate enough to include him with all of his difficulties,” said Klein.

Inside the invite, Ainsley wrote:

"Carter sat beside Timothy at school and he always talks about him. I really hope he can come. We are renting a bounce castle that we can attach a small bounce slide at the bottom. We will also have water balloons and water guns. Maybe Timothy can come earlier in the day if it would too much with the whole class. Let me know so we can make it work."

Klein said the simple gesture moved her.

“This mom gives me hope for Timothy’s future when sometimes I get stuck in the darkness of his diagnosis,” Klein wrote.

The party could not have gone better.

“Timothy recognized Carter right away and ran right into the inflatable minecraft castle. It almost took my breath away how easily he fit in,” wrote Klein. “I had to stop for a minute and reflect on how this could have gone and immediately felt guilty. How many invites have I declined over the years? Have I done my son a disservice? Perhaps. I’m not one to live in the past however, and moving forward I will continue to keep trying to be the best mother I can to my children in all aspects of their lives.”

She told ABC News that in the year that has passed since, she has become great friends with Ainsley. Now that the blog post is resurfacing, she says she hopes it spreads an important message.

“I want only one thing for our kids – for all kids, really, and that is inclusion,” she said. “All they want is to feel included and accepted for who and what they are – that different is OK … it’s just different,” said Klein.