What are good reasons to file a restraining order on the ex spouses behavior?

Almost 4 years ago, I divorced. The ex spouse would come pick up one of the 2 children and come right into my house like he owned it and even look into my fridge. Then after many times of telling him to stop doing that he would come over and knock then just enter my home like he owned it. After MANY times saying, do not enter my home he started coming over unannounced and I found that invasive and he continues to come over unnanounced and I continually tell him to email or call (his kids have cell phones) before. After my blood pressure starts to boil and I act like a angry idiot telling him to stop coming over like that (in front of my teen-ager, 2 grown kids. grandchild and eledrly mother) he continually does it. I can not stand it and need advice. Everyone gets agitated. Me especially. Obviously he doesnt listen. Today, I had yardwork planned and the kids were to help me and he comes and talks them into going to a party. He knew about the party way before today and could have emailed me and told me he was coming over etc. I have also had to block his calls from my phone because of arguments that upset me. What the heck should and can I do. I am in the Midwest area of U.S.