My ex and I have been broken up for 2 years and he still feels the need to reject me?

Long story short, my ex (30M) and I (29F) have been broken up for over 2 years now... we still have to remain in constant contact due to the fact that we have two kids together. Why does he still feel the need to clarify that he will never ever get back together with me even after 2 years of being apart? We agreed to do something together with our kids as a family and out of nowhere, he felt the need to tell me "not to get the wrong idea" and that he has no intentions of reconciling.
My ex and I have been broken up for 2 years and he still feels the need to reject me?
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