Relationship with mother

I have a strained relationship with my mother. Although I try not to be affected by the things she blurts out, I have over the last several years had to keep her at arms length = we only messaged via Whatsapp (which gives me the space and time to digest her blurts), but haven’t been telephoning each other in years. Also, as she lives in another country, we don’t typically get to see each other. We haven’t since before the pandemic. I don’t want her to be gone and regret that I didn’t ‘get over myself’ and appreciate my time with her.

My question is: how do I re-kindle the relationship? And how do I stay calm when she says unintentionally hurtful things?