toddler drama

Lovebug90

I am expecting in 6 days, (hopefully) and have a 20 month old boy.  Lately he has become a monster!  He is hitting me and his dad whenever he has to get changed, go to bed, etc. and will scream a high pitch shrill whenever he feels the need.  I am getting very nervous about how this is going to work with a newborn!  I don't know how much he really understands about the fact that we are having a new baby, but it seems like this past week or two he has really been testing my patience...

Any advice?  TIA!