dps

My advice to the OP is similar to what I would tell my adult daughter.

File the police report. I know the police said it was useless to report the incident but that was from their perspective of proceeding with legal action against your ex partner. You can file a report with the police based only on what you said happened. It will be documented if future harassment occurs showing a pattern of behavior. Let the partner know that you have filed a report. This might be best if a lawyer were to notify him by letter instead of you directly. This would put him on notice that you won't tolerate his behavior.

Do a back ground check on him to see if he has any history of this or any other behavior. You can do the check yourself online. Most cities and counties provide access to their court records for free or a small fee. They also have a free sexual predator database you can access for free ( states too ). You can pay an online service to do the public record search or pay a private investigator to do it for you.

If he touches you or speaks to you at practices, respond in a loud voice identifying him, say stop or don't and what he did. example: BOB STOP BUMPING INTO ME!!
This may be embarrassing to you but much more so for him and let's everyone at practice know he is harrassing you (witnesses?)

Good Luck
dps