I can't comment from the perspective of bipolar since I'm not but I do understand anger.

Everyone is fundamentally afraid on some level, especially in the past few years but, overall, it's an underlying experience ubiquitous to being alive and sentient. Most people cope with their underlying fear by denying it, ignoring it, treating it (with meds, drugs, alcohol, extreme behaviors like sky diving, you fill in the blanks here), turning it inside (depression) or outside (aggression). Fear doesn't exist by itself and most Humans have a subconscious mechanism that turns it into something else. Those who struggle with chemical imbalance or whatever it is that causes "mental illness" aren't always able to use a subconscious mechanism (normally they're acquired in childhood as a coping mechanism for unhappy - or worse - circumstances). It isn't their FAULT they can't do that, it's the nature of their brain function. So occasionally (or, for some, most of the time) the management of fear is impossible and it turns to ANGER.

Even in the world of non-Humans, fear can turn to anger (there are three expressions of fear: fight, flight, freeze) and, sometimes, that anger can become AGGRESSION: striking out (dogs bite, cats scratch, horses kick, etc.) In the Human, aggression can mean violent displays of physical harm but, most often, it means lashing out at others.

So what you're doing isn't a deliberate verbal assault, it's a form of adult "tantrum" driven by fear the situation elicits (that you're not in touch with at that moment) that is defended by anger and expressed with verbal aggression. I think most people have experienced this at one time or another, at least, i.e., during arguments with a spouse or close friend, when they might find themselves saying to that person "I didn't mean it". Saying ugly things to someone is definitely not an unconscious act, the person certainly did "mean it" at that time; it's probably an echo of how the person was treated in childhood or a very strong acquired defense mechanism against verbal abuse the person received from a loved on at some point.

There is a way to address this and attempt to get some control over its expression toward onself (in depression) or others, but when you're bipolar it might be more difficult: that way is by really getting in touch with that anger in therapy. You need a very skilled therapist for this, someone you absolutely trust, because underneath that anger is an enormous amount of FEAR and HUGE sense of VULNERABILITY. It takes time, it doesn't always work (especially if you're very very stressed), but overall it does teach you to redirect fear into something else and not allow it to put you into a place where your anger reaction turns into verbal (or physical) aggression.

There are times anger is called for, it's an appropriate response. But sometimes it's best, to protect ONESELF, expressed in ways that don't direct it toward the person who "deserves" to hear it. Your psychiatrist must know a therapist capable of helping you deal with the fear you experience that expresses itself in anger. Ask for a referral.