Never raise your weapon to attack another Satanist even if they are dumb enough to curse you, primarily because this will make you also an idiot. In your case it doesn't look like you're in any 'danger' from this, which is good.
Especially if the person was not really cursing you and this is just some dumb assumption. You have to be certain this is happening, as the enemy confuses people constantly.
The enemy thrives on these misunderstandings to try to make Satanists harm one another or create hostility. This is how they work.
The Gods handle these and those who curse other Satanists for absolutely no serious reason, such as the superficial or non existent reasons that you write, are punished heavily and sometimes even gravely.
Do your own aura and the reflecting thing as other have recommended, and if they are cursing you, this will help on your defense.
The fact you do not 'like' someone or that you do not agree with their character, doesn't count as cursing. Someone is not 'cursing you' if they tell you things that make you uneasy, or things that you dislike. This is not 'cursing'.
In cases of dumb jealousy such as described here and misery, you have to distance yourself, especially if this is harmful.
No real Satanist would do this kind of thing to another. Also, because there are two sides to each argument, have you done anything bad to him? If you have done absolutely nothing, just do your own, return the any curses, and as for anything personal, the Demons will handle the rest.
If there is an actual curse, the returning curses and your GD will take this back and deal with the matter appropriately. If not, then the returning curses will return absolutely nothing to this person, so it's not an 'attack'. However, if you attack him while supposedly 'returning' curses, the shots then will be on you.
If you do this and take all your disgusting filth from the soul and throw them on him, even if it did not come from him in the first place, in which case he may be innocent, you're fucked, because this is an attack.
You can all your GD while you do the returning curses to manage the situation, or just call in Satan to send a Demon to deal with it. Even if you do not know it consciously, they will deal with it.