Yelling and belittling

I grew up in a single mom home and she was a yeller and name caller, as much as I hate it I have fallen into the same cycle. How can I stay calm when my 8,4and 3 year old don't listen and do not obey. I am very new to your system and am trying to learn all the things while teaching it to my husband and the kids while taking care of a newborn. We all have adhd issues which makes staying focused a real chore, oh yeah chores are another issue. My family and home have gotten out of control and I do not know how to get control over them. I'm new to being a homemaker and homeschooling and I have no real support system near me, everyone I know lives 3 states away. My 8 and 4 year old tell me no and are completely disrespectful to me and have started yelling now too. I need help and don't know where to start. I am currently reading your book a house united and watching every video I get a chance on YouTube. I don't want to yell or spank and I hate feeling like I don't like my.owm children because of their behavior and laziness. I need to change whatever is broken in myself but I don't know how. Cps has a currently case on me because my 4 year old keeps getting out of the fenced in yard and wondering off so I'm constantly watching him and not able to properly teach school or do house work unless I keep him inside and then that causes its own stresses.