some honest advice you wont like (and are trying to make an informed decision): dont do it.
i love flying and understand you want to do this but please bear with me for a second.
you state you have a FAA CPL and dont mention any 121 experience
so im assuming you dont have a lot of hours on a multi pilot aircraft? (if you have A320/737 time, that changes things a bit :-) )
with that background, there are "conversion" elements but you end up doing a lot from scatch (been there done that... you cant just walk in and take an instrument checkride etc. )
taking the ATP theory and practice will take time and money.
the issue is that, at the end of all that, your chances of employment in Europa are not all that great. (unless you realize that when you are done and then spend more bucks getting an A320 type to then realize you need to buy yourself 500 hrs of training).
airline hiring is often through integrated courses (yes, also from modular ones) but there is an element of luck involved that im not sure you can afford with wanting to pay back what will be more debt by the time you finish training. (are you fluent in any other European language? - that broardens options a bit)
GA in Europe is limited and flight instructing will not help pay off $100,000 of debt.
if you want to be honest with yourself, research employment opportunities with a frozen ATP and limited hours/no TR.
check out this article
http://en.wikipedia.org/wiki/Sunk_costs
best of luck.