The situation of your partner with his wife has two versions:
- He is only physically separated from his wife for job reasons.
- He is separated from his wife, though not divorced and will see her every time he visits his two daughters.
For the first case there is nothing for you to do. You are simply a victim of a cheat. The reality that you need to accept is that he is still married and he has you as a pastime. In this case you won't have the chance to achieve having a stable future relationship with him.
In the second case, the situation of visiting his wife is normal because there are the daughters to think of. Understand that this could cause you a lot of jealousy. The reality is that he will continue seeing her frequently for his condition as a father, with or without official divorce.
If the first case occurs, saying that he keeps his marriage, you don't have another choice than animating yourself and break up with him because in one moment of passionate enthusiasm and as a desperate way of keeping him at your side you might agree to a sexual relationship with him and get pregnant. Such circumstance could mean a responsibility that will mark the rest of your life, if it isn't shared with him.
If, on the other hand, he really has separated from his wife, although it is not legally confirmed, your chance to turn into his future partner increases but it doesn't necessarily mean that this relationship will be successful.
The age difference you have with him and your lack of experience can make you easily agree to things he demands because he is experienced and was already married once. He could only be looking for enjoying your condition as a young woman. Be careful. Under these circumstances there are many chances that you might be affected and hurt.
I recommend you to talk to him as soon as possible and clear all your doubts. If you don't do it, you will constantly suffer. And if he avoids being confronted with you, than simply leave him. You are only 19 years old and still have a road way too long to be spending it with someone that is lying and only abusing you.