Rehabilitarme means "to rehabilitate myself." It's normally linked to recovering from addiction or injury, which makes it a striking choice when used to talk about heartbreak instead.
In "Quiero rehabilitarme, soy adicto a tu cuerpo" ("I want to get clean, I'm addicted to your body"), the singer compares his need for an ex partner to a real addiction, something he desperately wants to overcome through rehabilitation.
"Ayudame" is a breakup song that treats heartbreak like an addiction. The singer compares getting over an ex to going through therapy: he's stuck in denial, new to depression, and can't stop wanting to kiss her even though the relationship is over.
The chorus leans into dark humor, common in regional Mexican music. He jokes that his therapist is tired of hearing the same story, and that the promise of "together forever" fell apart. He'd rather she hang up on him if he calls drunk, or tell him to get lost if he begs her to come back, because he doesn't trust himself to stay away otherwise.
By the end, he compares his feelings for her to a physical addiction he wants to recover from, admitting he can't do it alone, which is exactly why the song is called "Help me."