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.Just because you are in love with someone does not mean you can (or should) proceed with that person toward marriage.
The reality is you are in a drama that probably will never end.That is my general overview of handling situations like you are in.Now you need to confront the specific factors before you can make an informed and wise decision.Whenever you are involved with someone who has a past of any kind, in this case a past marriage, you are taking on all the people involved as well, and the history.How successfully you deal with it depends on many factors. You must consider all the factors and determine if you can accept them.That would be the biggest tragedy of your situation. I will assume your boyfriend and his ex-wife are both Catholic and were married in the Catholic Church.I know that he is Catholic, but you did not mention that she is.I also do not know if their marriage took place in the Catholic Church.I am just going to assume it did and the marriage was not annulled.As I’m sure you know, a civil divorce does not dissolve a sacramental marriage.All it does is help settle the legal obligations to each other at the civil level.