Divorce from bed and board is simply a forced separation. If he is out of the house then you are separated. Change the locks and tell him not to come back.
As to both your past affairs…My opinion (which isn’t worth much) is that they canceled each other out. As to his most recent affair… He committed marital fault and if he is the supporting spouse then he would probably end up paying you alimony. BUT, given your past “faults” he might argue that you also were at fault and he owes you nothing. Just my opinion.