“I visited the store where I used to work and went drinking with my former colleagues.”
“Former” is used with things that someone or something used to be but no longer is. For example, if you give your cat to your friend, the cat is now your former pet. If you get divorced, your ex-spouse could be called your former husband or wife.
「以前働いていた店を訪問して、元同僚と飲みに行った」
Formerは、人や物など「以前はそうだったけど今はもう違う」という時に使います。例えば、自分の猫を友達にあげたなら、前は自分のペットだった猫です。もし離婚すれば、以前の配偶者は元夫・元妻とも言えます。