Dtr OCD, BiPOlar, Drinks, Smokes Crack

My 42 yr old daughter has let us , age 65, and her sister, 39, raise her son but with occasional disastrous visits with her. Her dad, 69, livng out of state,
sees the boy, 10 , rarely. The boy has been with us since Sept 2008 and his mother was liivng out of state in a homeless shelter for addicts (she knows the director personally). For 3 years she has come back here, paid for by an 80 year old cruel man, who Each Time has kicked her out , at night, in the cold and usually calls 911 on trumped up charges. She hangs around men for 3 wks then goes back to the shelter for a few months, then she comes back here. She has been back here in town for 3 wks and we are losing our minds.
She is worse: she smoked crack one night at some guy's place, she chews ice 24/7, refuses to work, has one dollar, drinks, tells her son the "F' word,
sleeps a lot when she's with the old man, calls us too much crying, last night he kicked her out in 38 degrees and they HITCHED A RIDE WITH A STRANGER.
She said, "I HAVE A NEW BOYFRIEND!!" and my grandson was excited. She has been divorced twice all drug related, took 52 xanax of this old man's in one week which is why he called and told me they broke up. We keep telling her not to come here; to stay in dallas. We should get custody of him but he says she will kill herself if we do (she has been threatening suicide since age 18). The old man said, "I will get u an apartment and a car if you'll get a job" and she thought that was terribly unreasonable of him and they got in a fight.
I've lost 5 lb, have no interest in anything, my husband is 100% supportive and wants her Out of Our Lives Forever but she keeps coming back. She leaves 1/2 a ton of her clothes in our cars. She has neglected her son all his life and says she's a good mother. I called CPS in '06, they went to dallas and she ran away. She lived with a successful bachelor in '08, he took her and the boy to the circus and she left them and didn't return for 3 days.
She never sells drugs so she can't get arrested. With the ice chewing I know she's getting worse. Should we take the boy and move across country?
Or would she find us? She has NO car. Four cars were impounded her dad got her for no license plates or drivers' license. Her son loves to visit her but oh, the language that child has heard from this old man. Horrible.