1, according to what you said in your question, you didn't know you had a heart attack until the other person was sick, so you can rule out intentional homicide.
2. It depends on whether the other person died because of a fight or other reasons. After all, there is an interval of two or three minutes, and anything can happen. If a fight leads to a heart attack, it is a negligent death, and your relatives may bear criminal responsibility. If it is for other reasons, it has nothing to do with your relatives.
If you have any questions, you can leave a message further.