The end of Dexter Season 4

I am dissapointed by the end of Dexter season 4. First, the line was crossed from vigilantism to murderer when he killed an innocent person, and then was responsible for another innocent person's death. The trinity killer said it best when he said "but I don't take pride in my work." Dexter could have killed him earlier, but wanted him for himself, leading ultimately an innocent woman's death. Not just an innocent woman, but the love of his life for the entire series. Speculation about the next season is all over the place now. Was Trinity's family in on the murder of Rita? How will Dexter not lose his shit next season?