From the article "The Empathy Trap" by Robin Stern and Diana Divecha in June's edition of Psychology Today:
"Overly empathetic people may even lose the ability to know what they want or need. They may have a diminished ability to make decisions in their own best interest, experience physical and psychological exhaustion from deflecting their own feelings, and may lack internal resources to give their best to key people in their life. What's more, unending sympathy creates vulnerability to gaslighting, in which another person negates your own reality and asserts his or hers."
"Those who regularly prioritize the feelings of others above their own needs often experience generalized anxiety or low-level depression. They may describe feelings of emptiness or alienation, or dwell incessantly on situations from the perspective of another."
"Reining in overempathy requires emotional intelligence; its underlying skill is self-awareness. You need always to be prepared to explore and meet your own needs. Since you're not used to thinking about them, you might not even be fully aware of what those needs are. Whenever your empathy is aroused, regard it as signal to turn a spotlight on your own feelings, Pause (taking a deep breath helps) to check in with yourself: What am I feeling right now? What do I need now?"