Dealing with Negative Self-Talk: Creating Multiple Voices in My Head

The voice in my head, whom I've decided to name mike (cause why not, it's my voice), had been making a lot of negative comments about recent dumb things that I've done. So to combat him, I created another voice in my head, whom I named Jessica. Her job is to override Mike's negativity and say positive things that have happened to me. So far it's been working, my depressive episodes have been less toxic today, but I'm not sure if having multiple voices in my head is a good thing (and no, I can't kick out Mike, Mike is like my default voice in my head. He's been there since I was born). Is this a healthy course of action?