Period!
When someone reacts negatively to your boundary or your unwillingness to explain yourself further, it's often a reflection of their own insecurities or discomfort. Your boundary-setting and refusal to engage beyond what you're comfortable with is an exercise of your autonomy and self-respect.
You also don't have to reveal personal information to appease them or to explain your boundary.
Those who personalize the lines of others have a twisted mind because they perceive other people as an extension of their own agendas and that's not the case at all, we are individuals with our own rights, and as long as we harm no one, we have a right to exist free from interference from people who take boundaries personally, and like to retaliate.
How they choose to interpret or respond to that is ultimately their responsibility, not yours. It's about owning your power and not allowing others to dictate your boundaries or manipulate your decisions.
You don't have to explain yourself to people that you're not even close with! You can say something in a nice tone, and some will still find a ways to twist it against you, you cannot win over the haters.