I have not faced that exact situation, where the type of thinking you described happens for any and all situations at hand; but, I have faced that situation across my life and can think of a few scenarios at the moment. For example, if my girlfriend is out in town with her friends and alcohol is involved, I worry in general and then there are moments when I do contend with worst case scenarios.

I don't think that computing worst case scenarios is devoid of light, but it can be rough.

What I like to do in these situations is to pray to God. I like to seek refuge at God, from Satan the rejected. I believe God is the Eternal Refuge. I seek refuge as many times as I feel the need to. I believe imploring God is a form of worship, and worshiping God is good, therefore I continuously implore for things, including refuge.

Hope it helps, and that you have a blessed night.