回复：what is the bottom line to call the police?

You have to decide based on what is unlawful and what is criminal. Unlawful acts are not always criminal. I think the bottom line is really that if you feel that you are in the immediate danger of assault or battery. Particularly in assault, if you are in immediate fear that he would hit you, then his conduct is criminal and police intervention is necessary, even though he may not have such intent. Those conducts such as setting something on fire, are criminal enough to me. If I were under the same situation I would feel immediate danger of bodily harm and I would call the police.

Find a woman abuse support group in your area and ask for their advice. They would not mediate unless having your permission. This way, you would at least have a record or everything.