Do you want a friend whom you could tell everything to, like your deepest feelings and thoughts?

like 为介词 = such as

You want a friend

You want a friend You could tell everything to

缺少宾语

a friend

whom who that 不填

从句起到修饰作用，修饰前面的名词 a friend.

You want a friend to ______ you could tell everything

定语从句

whom