I am so sorry that you are feeling this way.  First I want to say that there is not a compeition between you and your husband for your childrens affection.  So you may not like to play make believe, but perhaps you will read a book, or teach them to fold clothes, or bake cookies, or something that is  yours with the kids.  Your son is still very young, and I am wondering if you are still dealing with some post-partum issues?  Have you discussed this with your Dr?

Make sure your husband is helping with the after work-work load. The work load at home, so that you do have time to breathe when you get home from work. You can't do all the work, while he does all the play.

I remember feelings of frustration because I couldn't get my children to do what I needed them to do. Just know that is normal from time to time. But since you say you have struggled with this since the birth of your daughter I really think you should seek some assistnace from your doctor.