That substance is called cocaethylene, which is produced by the liver in the presence of cocaine and alcohol. Cocaethylene is a metabolite which is much more toxic than cocaine alone (Julien et al., 2011). As indicated above, this combination can result in death much more quickly than in the presence of cocaine alone.
I've seen cocaethylene referred to as "supercoke," and it's pretty bad news...
In addition to that, a side effect of cocaine and alcohol is stroke and alcohol and xanax can lower respiration, which in combination with cocain would lead to asphyxiation and/or brain damage from lack of oxygen under increased demand... stop taking advice from your drug dealer is my suggestion... they're trying to kill you or sell you more shit. Maybe trying to get you dependent on meth or something to compensate for the brain damage they've caused.
You need to treat yourself for stroke and asphyxiation... and potentially some form of liver damage which won't show up on routine blood tests. Most doctors have never thought about saving a patient from drug abuse pathologies and users and take the stance that you've done it to yourself and deserve it... which is quite inhumane in my opinion but appears to be the truth?
Here's my guess as to what might help you, but I'd contact a professional... I'm guessing LEF could do you some good, but I've not seen a rehab center that will do anything but help you cope with the brain damage and I'm just hoping LEF can do something for you.
Anyways... I'm thinking
Grapeseed extract or pine bark extract (increased blood flow)
Rutin? iirc it helps improves management of vasodilation/constriction in finer vessels.... maybe it was purslane?
Pregnenolone (good for strokes)
Progesterone?
Alpha GPC
Taurine (a few grams) for liver health
Milk thistle for liver health
Vitamin C AND Ester C
Perhaps tocotrienols (with low or no tocopherols), and if you take this it should be safe to use IGF1 as well
Blueberry Extracts (good for general brain health)
Quercetin (senolytic to help replace damaged brain cells?)
Lion's Mane?
Bacopa?
Imagine there might be more and better for what you're going through... so I'd definitely be looking for a drug abuse recovery specialist or hoping LEF can help.