You were on the right track, "extinction" (completely ignoring his tantrum, including not showing an stress or emotion that he might detect) for the tantrum behavior is what I would have done as well. Just know that initially, you may experience the "burst" (increase in tantrum severity) before it goes away, though rest asured it will, provided that it is done correctly.

You can consider "antecedant manipulation" in preparation so that this does not occurr again (insuring that he does not see the pillow (or other preferred item) before bedtime, in this case). Or offering a choice of some other preferred item which is more beneficial to you at bedtime.

Since she is not following your lead as of yet, invite Mother to attend courses or read paragraphs along with you so that her efforts are in sync with yours.

For any parent, I would strongly recommend taking a parenting class or two on behavior. Some places you could find such a class probably for free would be through CARD (Center for Autism and Related Disorders), who are affiliated with numerous universities across the nation, probably one near you), PHP (Parents Helping Parents) who are also popular in many state I believe, or asking on this website. My wife and I took three courses and have worked with three different behavioral service providers who use the same principals, so with the repetition, it becomes natural overtime and you can get oustanding results (other parents complimenting you on your child's behavior in a restaurant for example, has happened to us many times since taking the course, whereas my daughter had terrible tantrums all the time in public berfore, now almost never.

A couple of very good books on this topic are Positive Parenting by Glenn I. Latham, and SOS Help for Parents by Lynn Clark.

It's important to be consistant and no you shouldn't give in. But as evak77 points out, pick your battles. Try to redirect your child to something else that will grab their attention when you can.

The answer is no you do not always want to give in, but as parents we tend to do just that to avoid the tantrum but in doing so we are not teaching the child proper behavior.

In these kinds of cases I would call that picking my battles and sometimes you just want the tantrum to stop. This is where ABA comes in because using it will help to teach the child how to behave properly. When these situations come up the child is better able to tolerate things they do not like. If you keep letting these things go they will get worse, they start small and then get worse. If you add on top of that the child getting bigger and stronger that just adds to the problem.

Try to start in small steps and teach your child about Shari g and playing appropriately, when the do the right thing you reward them and when they don't you do not reward. This is going to take a while it will not happen overnight just keep working at it. Also try to get your child ABA services