My ex from eight years ago and my security clearance?

Hello, So I am getting a security clearance for a job and it requires to list any past weed use so about eight years ago a guy I was dating at the time, him and I did weed once so I listed it on the form since it said the last ten years and it was about eight years ago. We also broke up about eight years ago and it wasn't on the best of terms and he has been with someone else for several years. I know that someone from the government will likely want to talk to him about it as part of the security clearance process and it makes me kind of stressed about it because I don't know if he will be mean. I was completely truthful for the form it is required to be listed but I also heard the someone from the government might show up to where he lives and ask him about it so I thought about sending him a message about it to let him know in advance but since he's with someone else for several years I don't know if it would not a great decision and because we didn't end on good terms as he dumped me and was not very nice about it. I just don't want him to think that he will get into some trouble if a government official shows up asking him about weed use since I think he still uses weed but we also haven't spoken in eight years.

Should I message him about it or are you not supposed to let anyone know? I have heard different things.