I had a car accident. My ex-boyfriend texted me that I must be careful when driving. It's been a year since we broke up.

It can be understood as normal ex-boyfriend care. Even after breaking up, it is normal to know such news and care about it. It also means that he regards you as a good friend.

It's been a year since we broke up and he still cares about you. Whether he got his information by accident or kept paying attention to it, he sent a text message anyway, indicating that he knew and expressed it.

He didn't choose to call, but sent a text message, which shows that he still has scruples, fearing that you will misunderstand or that people around him will misunderstand.

Well, just warm up. Don't think too much. If you reply, you only need two words: thank you.