Bringing Down the Hammer

I really need help.  If you're a parent of a toddler, please, give me a word of advice or encouragement... anything!

I'm having a hard time reeling Marco in since we moved to Miami.  I don't know if it's the change of environment or living at my in-laws house, but he's becoming majorly defiant and unruly.  He pretty much takes my "no" as a suggestion and usually does whatever he wants instead.  It's hard for me to always be hands on with him because more often than not, my hands are tied up with Jonas.

When I call his attention, "MARCO", he responds with an equally loud and demanding, "MAMA".  This is unacceptable.  He also swats at me, as if threatening to hit me.  Again, unacceptable.  I feel like spanking him for hitting is counter productive and honestly, it doesn't even faze him.  Because of my arthritis, I can't hit him hard enough to make any kind of an impact.  He doesn't care at all.  And speaking as honestly as possible, when he hits me, I want to go nuts on him... I hold myself back, obviously.

Yesterday we had lunch with a friend who also has 2 boys the exact same ages as Marco and Jonas.  Her 2 year old was seated calmly in a booster chair, eating with a fork and drinking from a regular cup.  Marco... not so much.  He threw his plate... twice.  He threw his cup once.  He hit at me.  He peed in his chair (I'm convinced on purpose).  I ended up having to put him in a high chair to restrain him.  He was acting like an animal.  I was so embarrassed and I honestly didn't know how to handle the situation.  I told him nicely to calm down.  I told him harshly.  I grabbed his face.  I pinched him.  I spanked him.  NOTHING WORKED!

My fear is that he's gonna continue to defy me and disregard my authority and I'm gonna have to call Nanny 911!  haha.  No, but seriously... we're going through a really rough patch here.  I'm beginning to feel worn down, dealing with this 24/7.  My dad says we need to be super consistant... and I agree.  I remember from my teaching days, that consistency was key.  But jeez, is it exhausting!  Sometimes I wanna lay on the couch and put up my white flag... I SURRENDER, do whatever you want.  But I know I have to win these daily battles now or else deal with the consequences later.

Teach me how you "bring down the hammer" in your home?  And, if you don't have advice for me... then just pray!  haha... for real.