The Other Guy

After being in a relationship for 7 years with a man I thought was the love of my life who we share a child, I only recently recognised that our relationship ended atleast 3 years ago. Not only was I with for him for our child but I believe there was no love for a very long time and we both tried to make it work. Being honest, I stopped trying because he was not the man I fell in love with and unfortunately our relationship suffered, we talk but to maintain a smooth partnership for our child. 
I met someone else in 2016, approximately 7 months ago he is amazing and the most caring & focused man I ever met. Only issue is am still in my relationship that most likely has no future and also the new Guy is about to be a first time father but says would like to pursue something with me. What would you do if this was your situation? Do you trust your gut instinct or you continue where you are knowing very well the existing ship has sailed. 
Please advise.