Boundaries are about what is good for you and not what "they" should or should not do with their own lives. Setting a boundary doesn't need approval or even understanding from anyone else.
For example:
I need to take time for myself, for some therapy and to find my balance in life and to treat myself well. If you don't respect my boundary then I will cut all contact and make sure my personal emotional, physical and spiritual needs are in a healthy place. PERIOD. THE END.
Then don't take his calls, don't read his messages, or those from his family, or better yet, change your number.
Dear girl, you deserve to treat yourself well right now (and always). Don't let the "guilt button" do you in!
And then once you have declared your boundary, protect it and yourself as if your life depended on it....because it does.
Good luck.