I dove for 9 years, through college, and the trick I always found is to just do it as much as you can. The more time you spend at 3 meter (or 10 meter) the less fear you have. As an example, went to a practice about a year ago after not diving for 3 years and it took me a lot of time bouncing the board to get comfortable throwing dives again.

Spending time higher up also makes coming down to a lower height that much better. Train on 10M for a full day and then come back down to 3M and it seems like nothing. Was a good strategy to break your fear. One of my coaches (from Hungary) her father was her coach and used to dangle her and the other new recruits from the platform at a young age to break their fears. Not a strategy I would use with my kids, but worked for her (a 1988 Olympian.)