You are a good person! Any decent person would help, I hate it when people aren't "animal" people! Where I work we have a cat who has been there for 20 years we took him to the vet the other day for a checkup (he is super healthy) and everyone kept asking if we were gonna put the "stupid cat" to sleep! Um why?!? He is healthy!!!!!
But you did the right thing that poor dog needed help even if it was to end his suffering