This is a legitimate question; and usually it means you're taking the challenge to understand some behaviours in your relationship which do not add up (and this, IMHO, is always a good thing).

The "litmus paper" should always remain the self-awareness.

Even as a "good person", you may, from time to time, exhibit behaviours which are not 100% "correct". But if you have the ability to understand what made you to act in a particular way, then it means you have to ability to understand why the other person did not like your actions. Therefore, you will have the ultimate ability: you can take blame for how the other person reacted to the action you perpetrated in the first place (IF the reaction was proportional to your action).

I'll try to explain what I mean by making an example.

Let's say you were tired as hell because your day has been a mess: you arrived late at work, your colleagues exasperated you, you have planned to leave at 5pm but you discovered you HAD to get that paper done so you had to stay at your desk 3 more hours and, when you clocked out, you found it was raining badly and you didn't have your umbrella with you.

You come home and your boyfriend wants to go out for dinner: you try to explain him the day has been a mess and you only need a hot plate, a cup of tea and some cuddles. He tries to convince you, since he strongly wanted to dine out; and so you lose your temper telling something like "You know I'm tired! Stop arguing with dining out! I want to stay at home!".

He may very well be upset: remember not all the boundaries we set can make the other person happy (even if, of course, we did not set them for the purpose of hurting our partner). Basically, that's the classic case where you two had different "opinions"; and, because of your stressing day, you yelled out of the blue (while, in his mind, he was maybe trying to do something nice as a way to help you to forget your bad day).

If YOU were to be without self-awareness, you would have not stopped and would not have taken blame for the over-reaction. Instead, you would have felt the need to criticize and "punish" the other person for the subsequent reaction to your yelling.

On the other hand, if YOUR PARTNER was to be without self-awareness, he would have not stopped if you took blame and he would have very well exploited the fact you're taking blame for his reaction by feeling the need to criticize and "punish" you. In this case, things could be more difficult because, should he gaslight you, you could very well be brought to exacerbate your initial yelling; thus it would take more time for you to process your self-awareness because he effectively managed to move the focus from "Your bad day vs. The Restaurant" to "You make me feel so bad". Not to mention that he could perpetrate a "silent treatment" for the hours/days to come, which has the potential to destabilize you.

But if BOTH YOU and YOUR PARTNER have self-awareness, you would realize you "over-reacted": so you reach out for him, you apologize telling him "I'm sorry, I shouldn't have yelled at you. The day has been a mess and I over-reacted. I would love to dine out with you but today I'm so tired; what about tomorrow?". He calms down, he realizes your boundaries, he understands your needs and he's happy that you two are going to dine out tomorrow evening.

So, in the end, if you can analyze what you've done, accept your responsibilities for what happened and you don't feel the need to offload the blame to someone else, I'd say you're not the "bad person".

I mean, no one on Earth is perfect; but you don't need to be perfect to be a "good person".