Crazy Grandma! Please help!?

I don't even know where to start...First of all we come from different backgrounds..Ever since I our son was born his grandma has been very controlling and has very little or no consideration or respect for me as the mother. There's has been various situations where I have felt she has been unreasonable. Some examples- she insisted on picking his middle name and not including my last name even though we were not married or together at the time & I caught her with her in my sons mouth one day..I thought i had forgot his pacifier and was going to run to the store. Once i got to the car in the drive way I saw the pacifier on the seat and came back in...I stepped out for less then two minutes! i never said anything because i didn't want to overreact since our cultures are different but it has always been on the back of my mind. so yesterday his dad decided to leave him with her for a couple hours so he could run an errand and I decided to call her to clear things up and just let her know I want her come to me first before she makes any decisions regarding the baby that may be questionable. my intention were good. I wanted to have a good relationship with her for my son. Since i had never brought up the issue I decided to start with that. Well as soon as I brought it up she flipped out and started yelling at me saying that was a long time ago and what was she soppose to do he was crying so bad(exaggerrating!) and how i dare call her with that. I kept trying to explain the reason for my call but she wouldnt let me get past two words and hung up on me. i was so angry I couldnt even have an adult conversation with her. i decided to pick up my son early and left work. On the way there her husband calls to tell me she called him complaining I was disrespecting her!!! I explained to him how the conversation went and that it was actually the other way around. When i got there she had an attitude with me and started going off about random things saying I had disrespected her when I didnt give him the middle name she wanted(in her culture it was traditional)but I dont have agree with everything-she continued saying i was also disrespectful when i was late to a naming cermony held at their house seven days after the baby was born( i was still recovering and also have a 4 year old daughter to get ready by my self) she never cared about how i was feeling....she kept saying in her culture as the grandma its okay to do what she was doing and so on...and i still continued to get cuttoff and could bearly get a word in i told her I had never yelled at her and would like to talk things out and she just kept saying no she refused to get disrespected. I told if my son was going to be around her we needed to work things out but she refused to let me speak and said as the mother I could stop bringing him over trying to make me feel bad. I told thats not what i wanted but appearently we cant even have a civilized conversation. She flipped out even more saying i was disrespecting her again calling her uncivilized. i dont know what to do! I want to work things out but it seems impossible with her! Is her behavior normal? How do I deal with this She wont respect my valid concerns or wishes.