OH, I'm so very sorry...the ones that are so trustworthy are just treasures, and so hard to find! Horses have touched my life in ways no other animals have, so I truly do feel your pain. I wish you the best in letting your kiddos know...
What a handsome guy. I love your farm. I am so sorry to hear that you had to put him down. Sounds like you have an excellent vet to consider the impact on his horse friend.
I agree with Chickenzoo, he was not "just a horse"
Oh what a beautiful boy he was. Darling, you can cry like a big ole baby all you want to, I willl even join you at 45 years old...there is no such thing as "it is just a horse". My sweetie pie mare was 24 years old when I had to make the same decision over recurring kidney issues...I balled for three days after. I was there with her in the beginning when she was going to be put down at two weeks old and in the end 24 years later and she was a lady through it all. At least he had you and your family to love and care for him through his final years...no horse could ever want more than that.
Do not worry about another horse...when the right horse needs you...you will find each other.