4 year old chihuahua to rehome

My dog's name is Walnut.
He has been with me since he was 7 months old.
He's now 4 years old.
I work all day and my kids are in school all day.
We are heartbroken.
But this has been hard on me trying to manage everything on my own.
And we just can't have pets right now.
He is a sweet dog, he would be best in a home with no other dogs.
And probably a female owner just cause that's all he knows.
Him being my baby.