I'm so confused, broken and lost - Could use some advice

So, here's my story. John and I were together for 8 years. When we got together he had a 3 year old son who I became a mother to. October 4th he started crying and told me he wasn't happy. I told him he should find someone to make him happy (stupid thing #1). He asked "You wouldn't be mad?" I said no. He told me he would always love me and I was his best friend. He moved in with his brother and left his son with me for 2 weeks.

The 2nd day of us being apart I took his son to his brothers house to see him. That was the night I found out he was seeing the girl who had been texting him flirty messages (that he works with) for the past 3 months. I was suspicious but wanted to trust him so I never brought it up. She was at his brothers house, laying on the sofa with him. I lost my mind that night. I told him he had to keep his son that night because I couldn't deal. I called him that night and begged him to come home (stupid thing #2). I poured my heart out, begging and pleading and he told me he loves this girl. After 2 days... because ya know he swears he didn't cheat. Oh, she was married. She begged her husband to stay but he left and John moved in after 4 days.

Those 2 weeks went by and we fought. A lot. He told me he had no feelings left for me and didn't want to see me, talk to me or be around me. Yet he would call or come to the house and sit for hours (that went on up until last week.) 2 - 3 times a week he would come here and stay for hours talking. Hardly any of that talking was about his son, but more what I did to screw up our relationship.

One day he was supposed to come see his son, I asked him that morning was he still coming he said he didn't have the gas (we live less than a mile apart). Not 2 minutes later he asked could he come over and use my computer....

I did some dumb things like changing his e-mail password - but I had a legit reason - our bank account was locked and I needed to reset the password. The confirmation went to his e-mail and I'm the only one with money in that account.

BUT everything that happens bad now is blamed on me. EVERYTHING. I haven't seen or talked to his son since around October 27. He wont let me have anything to do with him and has blocked my number. This happened after I was told his son (whom I still think of as my own) was at risk of getting kicked out since the landlord didnt' know they were there. I called the landlord and begged her to let them stay, told her John was a good man and I was just concerned about my sons wellbeing. I told John I called and that I couldn't believe he would stay there when he wasn't supposed to. He said the landlord knew, that the b* he was with told her. She called me an effing liar and said she told the landlord. I called her back and recorded her saying she didn't know they were there. That the b* told her John was just a friend that stayed there from time to time.

He said I tried to have them all kicked out and I will never have anything to do with his son anymore.

That's the gist of my life right now and the really horrible part is I still love this man. I miss my son; I miss my family and would do anything to have them back. But I would NEVER endanger my child's wellbeing. EVER. I just don't know what to do at this point - there has been no contact for several days besides me leaving 1 voicemail to tell him to change his phones info since I was getting e-mails as he was changing the password, security questions and all that.

Hmm I read all of your story and thought it was really heartwarming. Eight years is a long time. I just can't get a few things straight.

First of all, John's kid is not your own. I understand you love him feel that way but you gotta understand that the responsibilities are John's right now. At this very moment you'll have to focus on yourself.
Secondly, In a way you approved John of exploring feelings he had for another woman. There obviously was something happening between the both of you that made John unhappy. You might have something to do with that and it would be wise to reflect on this.

My advise for you would be to move on for now. Some time apart wil do both parties good. If the break up is definite than it would be wise to wipe him out of your life as much as you can. If you think about trying to get back together than you'll both have to make (and should be willing) to make changes and start on a long road of building things up. It takes two so John should also be willing. John should within a short amount of time reveal signs on his take on things, for as if he still does have feelings for you he'd want to make amends also. Setup a plan on how you want to handle things from now on because you'll have to play smarter in this situation.

I hope this helps a bit, take care.