Sorry to hear that you're hurting so much, things must be difficult for you right now as the were last night.

I chronically have dark nights of the soul and do similar things... then the guilt comes fast on it's heels.
But self-medicating ourselves like that can really communicate something to a MH professional. Primarily that the course of treatment that you're currently on needs some re-evaluation.

On an aside... you are not worthless. Feeling embarrassed is normal especially when we do things that we ourselves don't approve of.
That's you talking to yourself... overdosing isn't the way you want yourself to handle troublesome times. Right now you merely aren't aware of other, better ways of dealing with them.

I'd encourage you to talk to your T... and as for your feelings about your P-doc, talk to your T about that too.