So if you want to do the right thing for your boyfriend, and for yourself (and for the children and all others involved), you will end the dating relationship.
Maybe He does ultimately have it in mind that you will be married to this man in the future, but that is not for you to assume, nor to plan, nor try to manipulate.You need to step back and let God make this happen the right way, if at all.We were friends through his divorce and starting dating after his divorce was finalized. I love him, but have apprehensions about my ability to deal with this kind of drama. It probably would not surprise you to know that there are many Catholics in similar situations.I have believed God brought him into my life, but I am starting to wonder if God has something else in mind. Divorce is an ugly thing, no matter what angle it is approached.That is a wonderful thing, and should be your primary focus above all things in your situation.
I pray that you will not let anything or anyone disrupt your steps toward being received into the Catholic Church. Your entering the Catholic Church is the worst thing that can happen to the devil, so what you are going through is likely going to be used to shake your faith and perhaps attempt to get you to not become Catholic.Therefore, you are dating a married man, which you are not permitted to do.God cannot call a person to a vocation when they are already in a vocation.This would be the most important and objective aspect of your situation that I hope will give you clarity and also rest your mind, because it is a very liberating reality.Your boyfriend is still married in the eyes of God. And probably (assuming you were married to a non-Catholic Christian and not a Catholic) your marriage was also sacramental, according to Church teaching.It most certainly does not do anything to their moral obligations at the spiritual level.