Dear _________,
I’m sending you this little note to let you know how much I appreciate and value your friendship. This past week when I was going through a rough patch, you were there to lift me up with your wise words, and comfort me with your hugs. Thank you so much for being there for me. And I want you to know that if there ever comes a time you need someone to lean on, you can definitely count on me!
(YOUR NAME HERE)