I am in love with my best-friend?

Here it is, Me and my best-friend are separated from our spouses with pending divorces, we have spent a lot time in therapy with each other and formed a pact to not repeat the same mistakes. We have become roommates, do everything together and have planned future together,We have an "open' relationship and have decided to see what else out there, but we slept together and recently experienced a miscarriage which made my feeling more complicated. Recently in a argument he has stated that he does not want to settle down and wants to see what is out there. This hurt me because I love him but he was being honest.I also do not want to be a rebound. The issue is I do not know how to let him go and maintain the friendship. It has been very clear that when we settled down it will be with each other and He always tells me he is not going anywhere and the relationship we have is forever........How do I prepare myself to see him with other woman? or am I being strung along for the ride?