Proposal on the horizon, but so is fallout?

First time poster long term lurker and listener, my (31f) boyfriend (30m) will be getting engaged in the near future. I am over the moon about this. He is very close with his family and has a really cool dynamic. I however am only close with my mom due to several things that have occurred between me and my father. My parents are divorced and have been for a long time. Here's the issue, because I am low contact with my father, my bf only told my mother his intentions of proposing and asked for her blessing. So any posts after the announcement would be catching my father, a very traditional man, completely off guard. We plan on calling our parents after it happens to enjoy some time together before making it public. I don't want my fathers lack of excitement or worse his lack of care to ruin the moment but I also don't want to deal with the backlash should I forego the phonecall and post first. So Reddit, what should I do? Ruin the moment or deal with the backlash? Or a secret more efficient 3rd option?