Are people who are trying to recover from a drug addiction usually violent? Frightened of my boyfriend.

Caution! It is common for someone to experience depression, irritability, anger & frustration while going through the early stages of recovery. Rarely this can lead to episodic violent behavior. If he has been verbally or physically abusive, you need support and guidance to avoid injury. Al-anon is a support group for the families of addicts. Don't hesitate to reach out to familiy and friends.
Unless withdrawal. People recovering from any drug have withdrawals not voilent episodes they may use withdrawal as an excuse for an excuse but it is it not fear is not a good reason to stay ina relation ship but thatisa reasonable reason.