heading for an ugly divorce

Well found a message on my husband's phone saying "hey babe I miss you" the other day turns out he's been phone cheating for at least the last month or so according to phone records he lied straight to my face about talking to her on the phone and I made him leave yesterday and stay somewhere else and I let him come put his kids to bed.. I gave him the choice of staying and getting help with a counsellor or j leaving for got well he told me this am that he don't think he wants to try and work things out bc he can't promise that he won't keep cheating mind u we live in pa and she's in iowa. Now to my question I know I have a just divorce but does anyone know or and anyone help me with how I go about filing and getting the child support and alimony? I'm absolutely clueless and need advice bc he has till 8am tom morning to figure out what he wants if he's not gonna try the process is starting.. this totally breaks my heart as we have a 5 yr old and a 1 yr old and he's willing to j throw us away for a women in a different state he's never met.. please any advice would be great right now and I could really use supporters who been through this.. 😢