Ex-boyfriend calls after 3 years and says he still loves me?

Ok first I would like to say this guy was my first love and im sure I was his. We ended things badly and I have seen him a couple times but bale before he sees me and I have had dreams about him throughout the years and thinkg about him. He calls the other night to tell me he was hanging out with his old friend that I too hung out with and said he said something that brought up a memory and he had to call me. He has been dating this girl who is the mother of their son but says everything has gone down the dumps and they are splitting and they are on good terms. He says even when the relationship was good he always thought about me. He is really the sweetest guy ever and truly loves his family and friends. I always regretted losing him and now he has come back in my life. I'm 21 and he is 24. I am going to give this a chance after his ex leaves and im scared about being around his son 2 weekends every month. But it would be worth it because I truly love this guy and he says he has never stopped loving me. My Mom is thrilled because she thought he was the best guy ever and he truly is. I'm just scared about the son who is 2 I believe and his ex being jealous and not wanting me around their son. Any advice would be great!