What do i do if he makes me so happy but he my best friends ex?

I got out of a controlling and crazy relationship a few weeks ago and now I'm falling for someone who has been there for me throough everything and this boy really likes me and he wants to be with me. The problem though he is my bff ex.. they have been broken up for a while. I really like him and he's into me but my mom and gma think that I shouldn't go out with him because he's me bff ex. But my mom loves how he makes me happier and is always there for me. Him and I want to try going out but keep it a secret for a while then tell her. I don't want her hurt but I'm happy with him... I'm soo confused. What to do ?!