I am a non biological father seeking legal visitation rights for my son. I'm not on the birth certificate. But I have raisied him sense birth. I no longer want to be with his mother but I no if we split I will no longer be able to see him anymore. Is there anything I can do?

You will need to consult a good family law attorney on this.

Being that you are not married to the mother and never formally adopted the child (if you had gotten married) at this point I do not see you having any legal standing to see this child after you and the mother split up.

There is little you can do, you are not an adoptive father and a step father is not a legal family.

Unless the mother will allow you to see the child, sadly there is little you can do. Since you are getting a divorce anyway, ask your divorce attorney to try and get something added, but I suspect it will not fly though the court

Is the bio dad in the picture at all ? If not then have you been presenting yourself as the child's father ? If you have and bio dad is MIA then you might be able to convince the courts of visitation because you have acted in the child's best nterest and the father by default.
How old is the child and how long has the relationship been for ?