All of life requires balance. Too much of anything can harm you. So if you're constantly thinking about something in particular then it's probably taking up more time and energy than it should. It's also probably interfering with daily tasks. Therapy isn't just about talking (and it's not about fixing either), it's about finding that mental balance.

Nighttime is always the worst for me too. 99% of the time, if I have a breakdown, it will be at night.

There are coping skills for nighttime. Mine are: listen to music, light a candle, aromatherapy, open the window and feel/smell the air and listen to the sounds, hot bath/shower, hot tea/chocolate, meditation/relaxation, writing, etc.