Hi ngates,
You are not over reacting at all. The root canaled tooth, although you had no obvious symptoms prior to the crown breaking, had been infected for the entire 10 years. All root canaled teeth harbor some degree of necrotic, infected nerve tissue inside the microscopic canals that are not accessible with an instruments, laser or medications. I will post a diagram of a tooth to show you just how tiny and how many of those canals there are in every tooth. Infected teeth do not always have symptoms of a problem until the problem becomes severe. So that could be why your tooth was asymptomatic, not healthy, just asymptomatic.
There is a great possibility that when the old crown was taken off there was decay found on the tooth which had to be drilled away. That is the reason why so much of the tooth was prepped for the new crown. It is typical to find decay under the crown of a root canaled tooth because the tooth harbors bacteria which eventually decays the tooth.
The drilling into this fragile tooth set off further inflammation to occur not just with the tooth but with the periodontal ligament that encases the tooth in the bone. This is why you had that feeling of the tooth being higher or swollen. It was the inflamed ligament that was raising the tooth up. The infection diagnosed after the placement of the new crown was just a proliferation of the infection that had been living inside of this tooth for 10 years. The drilling of the tooth stimulated the bacteria to progress further. It's important to realize that the bacteria would have progressed further on it's own eventually anyway.
The tooth could have been fractured long before it was diagnosed. Again it is typical for a root canaled tooth to fracture.
Regarding the placement of the dental implant..... dental implants are only meant to be placed in healthy, viable, disease free bone. Placing an implant in an area of bone where there was an infected tooth for 10 years is very risky. Therefore, ideally the tooth should be extracted, the bone debrided very thoroughly of the tooth in it's entirety along with the periodontal ligament and all diseased tissue and bone. The surgical site is then allowed to heal for about 3 months and monitored during that time with periapical xrays to be sure the healing is healthy. Then if the bone looks like it can handle an implant successfully, that is when it is placed.
Were you given the option of seeing an oral surgeon for this extraction? In the future if you should be in a similar situation, an oral surgeon is usually the best option for the removal of an infected and/or root canaled tooth. This is what they do every day, all day. General dentists, not so much.
Regarding the antibiotics.... if the jaw bone is infected, oral meds are not going to cure the infection irrelevant of how many prescriptions you take. Th implant will act as an irritant. So it is best to have a consult with an oral surgeon. Bring all of your pre and post op xrays of that area.
Also, it is never healthy for your intestinal and immune system to take repeated prescriptions of antibiotic drugs. These drugs destroy the healthy bacteria in the intestinal tract and can pre dispose you to an intestinal infection called D-differential. This infection can actually occur weeks after the drugs are stopped. So it is imperative to replenish healthy bacteria in your intestines with a supplement called a probiotic. The supplement should be taken an our prior or one hour after the antibiotic to avoid contradiction.
The ideal probiotic to take while on antibiotics is called Saccharomyces Boulardii. You can get it in most drug stores and online. The usual dosage while on antibiotics is start it asap, take 2, 500 mgs 2 x's a day. Here are two little blibs on it:
http://www.powerofprobiotics.com/Sac...boulardii.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3296087/
I hope this information is helpful to you.