I am not surprised you are having problems this sounds too much for a 2year old and your original gut feeling was best ,I see there are 2 step children perhaps they are older than your child and there could be some rough housing or overwhemling behavior.It would be best for your child to be with you the majority of the time at this age, yes it is good he sees his Dad but there could be some dynamics going on that are upsetting him its the child that is important , my opinion is, whilst he is this young he stays with you most , which ever way to figure it out.they may all be kind folks but if something is going on to cause upset you are enabling it by sending him aaa,it could also get worse ..Good luck