Ok first of all don’t stress, do not call him let him call you! he has already agreed to meet which is good.
Communication will be hard especially as you have a child together but keep it simple and to the point on Monday, access, money, come to an agreement! Do not be needy and tell him everything it will arise his curousity that your not needy or desperate.
Get a pen and paper and write it all down and the shred it, it’s clears your mind