Awareness or insight are valuable things to have. Some people with mental illness have no insight to their behaviour and their actions.
Humans, regardless whether they have mental illness or not commonly display periods in their life whereby emotions overtake logic. You can observe this often. At work, in the street, with family. Someone gets upset and no amount of calming or injection of logic seems to make a difference. They are in a "state" as we say. In a "lather". Made worse with alcohol I must suggest.
If we are aware of how potent our emotions can be on our thinking and therefore our actions then perhaps we can introduce a plan to self instruct ourselves. A u-turn of reactions.
There is no magic method. It's all about awareness. That your thoughts are not as logical as they would be without your emotions taking over.
A clear example for me was some comments my mother used to make under high emotion (I'm estranged from her and I believe she has cronic BPD). Normal logic comment "The frost got my tomatoes but the other vegies might survive ok" Under emotion "Oh, the frost got my tomatoes....I might as well pull out all the vegetable garden and start again. I'm a useless gardener". Now I acknowledge the above is riddled with other mental illness issues but you get my meaning that her behaviour under emotional "control" is vastly different, more negative, a greater impact upon family members. My mother had no insight and was never easily approachable as she took the most tactfully put comments as a threat. Terror resulted (when we were kids) or alienation or all out war pursued when we entered adulthood.
Also ramifications on family members or friends would continue. My dear old dad would likely rip up all the vegie patch following her emotional outburst. Then once she settled and logic returned she'd tell him "you shouldnt have listened to me".
Now admittedly that example is from someone that has a swinging mood issue that required treatment. But often some of us live in a world of extremes. So what can you do?
Of course always consult your doctor if you are aware of your emotional instability or you are told so. Often we have to rely on others to tell us if our behaviour is not stable be it mood, rapid pace of speech or other symptom. Take others observations seriously and not personally. That isnt easy but remember- it isnt easy for them either.
Everyone just wants us to be as well as we can be. It's their way of loving us. Love them back by listening.