152:15 If a man divorced his wife, they may not live in the same courtyard. If she subsequently married and divorced another man, or if he divorced his wife because she became forbidden to him, they must keep farther from each other and may not live on the same street if it’s closed on one end. If it is open on both ends so that large numbers of people travel between them, then it is permitted. An ex-wife who lives with a new husband requires even greater distance and may not live in the same neighborhood as her first husband. In all these cases, the onus is on her to move away from him but if she owns the courtyard, he must move away from her.
152:16 A man is permitted to support his ex-wife and this is a greater mitzvah than supporting any other needy person as per Isaiah 58:7, “do not turn away from your own flesh.” This is only the case so long as he doesn’t deal with her, but supports her through an agent.