Oh my G... definitely agree to temporary custody if its an option. This is your only choice...well you could say no and let the grandparents become temporary legal guardians??? Why in one million years, you are wanting to see and care for your child are you even asking? I am shocked! What are you trying to prove here? Maybe you are just truly naive legally...I know I have been, and still am in areas' I am not familiar with. So given that, temporary custody is not considered a legal excuse to forgo the chance of permanent custody at a later date. Given that this may/would happen (just assuming for the moment), yes, there is a future court date set for you and your ex....presume now its after 3 months from now...you have the chance to gain major credibility with temporary physical custody insofar as having a more firm place in your childs life whenever a permanent custody order may be set. (already the child would be back in Tn....that nips that problem in the bud)
Mind you, me and my ex went to court for years with changes in custody, shared, physical, before any kind of permanent custody was set. MY understanding (please correct me seniors if I am wrong) is it doesn't make a huge day to day difference whether the custody is temporary or permanent....if you are deemed fit to raise your child soley for the next several months...just take it for what its worth....its not like you will go back to square A after this, unless you manage to find a way to seriously screw up. I apologize I could not make my wording more succinct, clear, simpler. I simply wonder by your questions (via your ex's attorneys' phone call) if you are seriously contemplating, literally, throwing the baby out with the bathwater. You want a major role in your childs life....here is your opportunity, and you are asking if you should refuse????? The attorney does NOT have the right to give you permanent custody...ONLY the judge can do that, at the next hearing and frankly, I would wait and see whats happening then before you ask.
I would ASK (vs demand) that you have shared legal custody...as you will need to be able to make major decisions for the childs well being the next few months....child back in school in TN, taking child to doctor, dentist, making those decisions. Will there be a quick hearing soon to determine all of this? If so, where?
Also, do what you can to get childcare so that you can continue with Al-Anon, and whatever other support you need so that you don't wind up in the same dynamic with mom, ever again. Hands off, and in case it does come up at the next hearing or trial, get support and counseling/Al-Anon so you are working on your stuff. The person to benefit is your child.
Weigh out any issues other than the current emergency when you go to court later on....yes, get prepared but don't haggle with her attorney over them now.
Another option to consider, I think there are a few counselors available to do play therapy with children starting at the age of three (I started looking when my child was two...thats what I got back then), see if your insurance policy may cover something like that because this would/will be hugely confusing and disturbing for your young one.