Child in college, is it ok for me (40m) to tell him that his mom and I are 99% likely to get a divorce?

When my mom decided to leave my dad she told my siblings and I that it was going to happen, I thought it was good to know and was happy she told us. But I’m not sure if I should wait for the stbx to tell my child or if it’s ok to tell on my own.

Any thoughts or suggestions would be helpful.