Complex sentence: Ennis sees his family regularly until Alma finally confronts him about her knowledge of the true nature of his relationship with Jack which incites a violent argument and causes Ennis to abandon his connections with Alma.
Split into simpler sentences: Ennis sees his family regularly until Alma finally confronts him about her knowing the true nature of his relationship with Jack. This results in a violent argument, causing Ennis to abandon his connections with Alma.