She brings the boyfriend to your marital home at 3AM, and a boyfriend who has been under drug charges???? And you let this man around your kids? and let them sleep there????
this sounds nuts to me. I know you love her and do not want your marriage to end but this sounds awful.
She cheats on you, with someone on drugs, they both stay at her parents, a physical fight ensues, and probably your child that was with her saw it or heard it..and then they come to your house and you are worried about making them (your wife and her BF) homeless???
Do you think for one moment they are thinking about how you feel? do you think they would care if you were homeless?
My best advice to you is see a lawyer, get your legal rights down and walk away from this woman. Let her go sow her oats with this BF.
You deserve better than this, it hurts now but it will get better.
I have no idea why we hang onto to people who have made it abundantly clear they no longer love us, respect us or even care about out....Love? Thats not love...
Remember you deserve better than this....you need a partner who loves you, and commits to you...not one that cheats and runs around.
good luck you are going to need it