Looking back on it, I feel more sorry for Alex than Dan
Playing on an emotionally unstable, lonely woman like Alex as though she was a piece of meat was absolutely sick. Dan deserved everything he got and more.
That line that Alex says "Because I won't allow you treat me like some slut you can just bang a couple of times and throw in the garbage" essentially reiterates what I feel. Dan really treated women like dirt, he absolutely objectified them. He slept with another woman while his wife was out of town, threatened to kill her when she said she'd tell his wife, threatening his wife's perfect perception of him/their marriage, then shot Alex while she was pregnant with his child. Oh yeah, Dan was a total hero. Not.
Alex was sick. It's not fair to paint her out to be some kind of villain. The original ending was much stronger and more true to the story, but of course it wasn't satisfied for the misogynistic 80s audience.