How do you fix communication in relationships?

Please post anonymously. How do I fix the communication problem between my boyfriend and me? I feel like he never hears a word I say. Whenever we talk, it doesn’t matter if it’s a serious or silly topic. He always over talks me. Even when asked a direct question, he doesn’t give me a chance to answer. He just answers it himself and goes on about his business, or he’ll keep talking, never giving me a chance. A lot of times, I try to share very important things with him that can help with him the kids, and he misses out, but when a friend of his or a family member mentions the same thing, he shares the info with me like it's his first time hearing about it. Sometimes I get so frustrated that a simple convo turns into an argument because I end up raising my voice to try to be heard. Before anyone says, “talk to him and tell him how you feel.” I have tried that, but as I said, I am never heard and never allowed to get a full sentence out. I know it’s not good to keep your feelings bottled up, and I don’t. I have a couple of friends I have known since childhood and most of the adulthood that I can talk to. Which he doesn’t like because he doesn’t want anyone in our business, and he thinks some other man is going to use that as an opportunity to get at me. Honestly, I barely speak when we are together because I don’t like to argue. Oddly enough, we argue about that because he sees I’m nothing like this with anyone else, and he claims he doesn’t understand why. which makes an even bigger argument because I’ll use that as the chance to tell him how I feel and as usual I get cut off mid-sentence not being able to actually express myself and the convo will just be him talking to himself repeating the same stuff over and over and even answering his own questions and eventually I’ll just let it go and go find someone else to talk to. I won’t even call him for an emergency. One night I was driving to work, I work the nightshift, and my car died right in the middle of nowhere. Now being that’s my man, I did call him first to come to get me. He didn’t know how to get to where I was because he’s not familiar with the area. I’m out there alone in the dark in the woods, scared shitless, and I’m trying to give him directions, and all he kept doing was cutting me off and talking over me. Some guy stopped to help and even offered to give me a ride back home. He was even trying to tell me how to help my boyfriend get there easier, but of course, I couldn’t speak. Finally, I got so mad I lied to my boyfriend, told him everything was fine now, and end up spending 30 bucks to take a cab home.