It sounds like you work for a group, and not your own clinic. As such, a lot of the concerns/obligations that would follow if you were running your own sole practice do not apply, such as the whole 30 day notice thing being given to patients before you are allowed to leave.
While I hate the term, who "owns" the chart? Likely the practice you work for, not you. The patient's don't sign an agreement with you, they signed with the practice. You are an employee, and one with a contract. That contract is your obligation, you can be as mercenary as you want about it. If you feel you need out, then go - as long as you fulfill your contract you've fulfilled your legal needs. Don't get me wrong, your professional responsibilities are still there when you practice, and liability for your action may follow you, but don't wrap employment law into it.
Real life example, my wife had a specialist, one day, with zero notice specialist is gone from the practice. (Found out details later, but long and not germane to this post). We found out when we arrived at the clinic for our appointment. The practice never informed us, but re-scheduled us with another provider in the group at the same time so we saw a new person at time previously scheduled for old provider. Said provider left shortly thereafter, we found out when we came for follow up, and found out we had been re-scheduled again. We stopped going back after I got the whole story on what was happening. Was this "nice"? No. Was it legal? Yes. Was it abandonment to lose our provider this way? No. The group which we had established with had other providers and maintained all obligations.
Don't be intimidated. Know what your obligations are and fulfill them and you are fine. I suggest looking deeply at your current state rules/regs.
TL/Dr version: If you call in sick, do all the patients scheduled have a claim for abandonment? No. If they fired you, what obligation would you have to your patients? None, if you quit without notice, what obligation then? None.
Me personally, I would've walked the day my manager threatened me. Don't ever work for an employer that operates by threats or intimidation. Makes for a bad life.