That is a complex question that might be hard to answer on a forum like this without further information. First, I want to assure you that whether you have children or not has no bearing
whatsover on whether you may enter the Catholic Church. Period. Anyone who tells you that is just not informed.
Now,we need to look at the circumstances of those children. You state that these children are from a "previous relationship." Assuming that you were not previously married, then you are immediately eligible to seek entrance to the Catholic Church. The normal route for this would be for you to enter the RCIA program in the fall and be received into the Church at the Easter Vigil Mass. You can get more information about this program from our web site at
http://www.saintlukeslidell.org/rcia
If you
were previously married in any form, there would have to be a determination if that previous marriage was sacramentally valid or not. Depending on those circumstances, you might need to have a Declaration of Nullity (commonly known as an annullment), before you can be admitted to full communion with the Catholic Church. You can read more about this and watch some videos on annullment on our website at
http://www.saintlukeslidell.org/annulment-support .
We hope that this answer has helped. You probably would benefit from meeting with a Catholic Pastor, priest or deacon. May God bless you in your journey to grow closer in your realtionship with your husband, God, and His Church.