You will need to file for divorce and request exclusive use of the marital home. That is the ONLY way she'll be legally required to move, and it will ONLY be when the court orders her to vacate.
I'm surprised the lawyer didn't tell you that.
In addition, ask for a no-paramour clause.
And, in TN, adultery (particularly during the divorce process) can affect custody, so I would ask for primary custody of the child while the divorce is pending.
Tennessee Divorce and Family Law
If OP does get the marital home, then there would be some strong arguments in favor of him getting temporary physical custody:
- Child gets to stay in same home
- OP says 50:50 parenting time now, so no preference either way
- Mom is committing adultery - and plans to be continuing while the divorce is pending