Speaker A: He wasn't in love with me.
Speaker B: I hope so. Otherwise, you/you would've/must've crushed him after you dumped him.
What's the correct alternative and why?
The loving (or not) and the dumping are events in the past, so the crushing would also have occurred in the past. Joining the two parts of the dialogue, you can clearly see that it's a hypothetical conditional in the past.
If he had been in love with you, you would have crushed him when you dumped him.
would have is therefore required.