You've been repressing some emotions. After a manipulative relative pushes your buttons, it will be impossible to hide these feelings any longer. An angry outburst will fill you with shame. Don't feel guilty for being honest. You've been subjected to shabby behaviour. Instead of putting up with this abuse for a moment longer, defend yourself. This bully will be astonished by your forceful response. It's clear the terms of this relationship have changed. This transformation is to your advantage.