Manipulative people latch on to empathetic targets and exploit their innate qualities. They find people who are easy-going, gentle and kind - who avoid conflict and seek to make others happy. The Problem: They reciprocate none of these things. Instead, they feel entitled to your constant forgiveness and self-blame. If you set boundaries or say no, you will be punished for reacting to their abuse. Toxic people constantly look to blame the victim.
His behavior will never change! You know this is who he's been for all these years. Lying and cheating. Only you can stop this by stop allowing him to come over. This will continue for another 6 years and you deserve much better. Stop letting him manipulate you!