If this key is reused, is even possible to find your private key(and this already happened in the past).
This is usually the case, for example, when considering signing transactions or signing messages and reusing the k value. In such cases of re-used and non-random k values, it is possible to derive the associated private key, as you say.
This is not the case here, however. Encrypting a message in this way only requires knowledge of the public key, not the private key. Otherwise, how would you encrypt a message to send to someone else? There is no way to derive the private key from this encryption process, even with reuse of the ephemeral key.