worst Mom ever!

I feel so bad. I have a five year old son with sensory processing disorder, a six month old daughter and I'm pregnant again. Since I have found out in pregnant I am so angry with my son and his issues have been driving me crazy. I feel so bad. I feel like all I do is yell at my son and I don't even want him to be around me. His food aversions annoy me, he cries about everything and refuses to listen to me no matter what I ask him to do. I feel so confused and frustrated with him and myself ... is it this pregnancy or am I just a jerk? I am beyond angry at myself for not being able to control myself and just love my son for who he is. Can anyone relate? Or give me some advice on how to deal with this situation? I am not looking for anyone else to tell me how much of a shit mom I am being I already feel like it I am just looking for some positive help for my son and I, please!