There could be various reasons why your ex reacted with anger when you sent her a text checking up on her after months of the breakup. While I don't have access to specific details about your situation, I can suggest some possible reasons:
Resentment or Hurt: Your ex might still be feeling hurt or resentful about the breakup, and receiving a message from you brought back those negative emotions.
No Contact Rule: Many people suggest implementing a "no contact" rule after a breakup to facilitate healing and moving on. Your message might have violated this boundary and caused frustration.
Misinterpretation: Your intention to genuinely check up on her might have been misinterpreted, leading to her perceiving it as insincere or as an attempt to intrude on her life.
New Relationship: If your ex is now in a new relationship, your message might have been seen as inappropriate or interfering with her current partner.
Personal Growth: Sometimes, when people have moved on and experienced personal growth after a breakup, they prefer not to revisit the past, which might have led to her anger.
Emotional Turmoil: Your ex might be going through a difficult time emotionally, and your message could have triggered some unresolved feelings.
Different Coping Mechanisms: People cope with breakups differently. While you might be comfortable with checking in on her, she might not be ready for that kind of communication.
Desire for Closure: Your message could have reminded her of unresolved issues or a desire for closure that she's not ready to address.
Boundaries: She might have set clear boundaries with you after the breakup, and your message might have felt like a violation of those boundaries.
It's important to remember that everyone's emotional journey after a breakup is unique, and your ex's reaction may not necessarily reflect on you as a person. If she expressed anger, it might be best to respect her feelings and give her the space she needs. If you genuinely meant well with your message, there is no need to feel guilty about it, but it might be wise to refrain from further contact if she has made it clear that she prefers not to communicate. Focus on your own healing and growth, and allow her to navigate her emotions in her own way.