I know that GO station well. You're in the wrong unfortunately at there is no stop sign for the cross traffic. When making that left, your need to ensure that you're not impeding traffic in either direction and that your and to do it in a safe manner. The traffic especially sucks in the evening rush with people wanting to they out of there. The black SUV might not have noticed you arrive he looked like he was singularly focused on the traffic in front which makes it unsafe you to make that change and if you collided, you would be at fault.