Me and my girlfriend pretty often have heated but respectful political discussions and recently we were discussing Stalin. She thinks that he was awful, mainly because of repressions, cult of personality etc.

When I say that repressions were actually good and Stalin didn't kill enough fuckers, she gets a little angry, but I can't seem to explain my position in great detail because of lack of knowledge.

In the case of the cult of personality, I say that Stalin WAS loved by the majority of soviet citizens because he did a shit ton of good for them, but she still doesn't quite get it.

What arguments would you suggest to use, or maybe something to read in order to deepen my knowledge on the topic?