A husband begins an affair with his dream woman using lucid dreaming technology, but when this fantasy woman begins stalking his family in real life, he must protect them from a woman who shouldn?t exist.

I'm a little confused by the threat. Is the digital woman communicating with the family? Does she now have a body? The trap feels pretty central.

I like this idea. The logline is definitely getting there. The SciFi elements make it harder because there's a bit of expositional stuff to get across.

At what point does the fantasy woman start stalking the family? Since it's a horror, I'm guessing probably Act I climax? But could be midpoint? That could have an impact on how the logline works.

If it's the Act I climax, then the inciting incident is the moment his family get their first threat. If it's the midpoint, then the protagonist needs another goal to get him through Act II.I (assuming a 3 act structure) until the first threat.

This logline is a lot better than the first.

I would change "A Husband" as your only description of the lead character. We know from the line "begins and affair" and that coupled with mentioning of his family he is married and is a family man, so I would try to use a couple of adjectives to help flesh out the character for the reader.