I think you should get married and repent of your cohabitation.
To fully do this, to understand why you need to repent, you should read some Christian stuff on the value of marriage. Catholics believe it's a sacrament, that is, a very important thing.
It sounds like you're living a continent life, but it's still very important for you to get married. It's not just an empty ritual, taking a lifelong vow to be with someone until death is very significant, and it gives our lives and bodies and your children the dignity they deserve.
God bless