Have Relationship Questions? Ask a Counselor for Answers ASAP
It would be important to know what he wants to do. There are many man who have several children and do not reunite with their ex. You are correct- he would always be a father whether to one or multiple kids. His time, energy and resources would be tied to them perhaps even when they are older.
You would have to ask yourself- 1/ would sharing them with others be all right and to what extent, 2/ what future does he want to have with you? (are you wanting kids of your own and is he willing to father your kids as well) 3/ what level of commitment is he willing to invest in your relationship- what are his goals of it? 4/ is he someone you trust completely (that he won't hurt you in the long run, or are you having even 10% doubt?
Ponder on these questions and figure out where does he stand in all of this. Then, your answer will come to you in a clearer view.