How Do I Go About So

DF been cheating he doesn't know I know ! We have a 3 year old and he's been distance (that's how I found out he was cheating!) I never left a man I've always been left and cheated on and stayed ! I want to leave how do I go about so? We are on the same phone plan however I did block him anyway and I will be opening up a knew line for my self! Tomorrow he is off from work and I know he will contact me being innocent ! How do I leave? We do not live together anymore since we were in the process of moving. Thank god for that I won't have to pack ! Ha Any advice and tips? How do I explain to LO? & When LO cries at night for him do I just ignore it