Just try to think it's never as bad as it could be. At least you haven't hit someone or something (hopefully) and the meltdowns are in private, not having a huge tantrum in public (again, I hope not, for your sake, it's one of the most embarrassing things that's ever happened to me - and it's been a fair few times now too).
I think I'll still have silly tantrums well into my thirties and for a long time afterwards. I remember a few months back me and my girlfriend were about to watch Pulp Fiction on video, and I was looking forward to it as I haven't watched it before. We were going to watch it with dinner, and the cassette didn't work ( I only had it on cassette) so I got frantic over it and ended up ripping it from the video player and chucking it on the floor before stamping and jumping on it repeatedly whilst shouting and swearing at the top of my voice, right in front of my girlfriend. She was a bit shocked and said I went too far, but I think she was also sympathetic because she knows all about my problems. I think partly the reason I went so mental was because I have this weird thing that I have to eat food with some form of media to keep me entertained, and I have to match the food to the media. If I don't have some media I feel like it's a wasted opportunity for some reason. Anyway, because I was spending so long trying to get the video to work, our dinner went cold, and again I was really looking forward to the dinner. I had it all planned out to perfection, and the reality didn't match the scenario I had planned in my mind.
Have you tried to get any counselling? I'm getting one assigned to me soon for anxiety aswell as things like this.
Aswell as the video fiasco, I got back from work once and went to get a shower, only to find that the water was running cold, so I chucked the shower head at the tiled wall, shattering the shower head and breaking one of the tiles, and we'd only had the bathroom redone for less than a year, and my mum was really proud of it (aswell as paying for it all) and I felt so bad that I did this. I spent the next hour or so screaming as loud as I possibly could in the foetal position naked and wet and cold. The guilt plagued me for weeks afterwards. I always do this sort of thing such as destroying objects, but it's bever my own stuff. In my hazy mind during a meltdown I see everyone else's property as just "stuff" that is meaningless, but as soon as the red mist settles, I see that I've broken something that means something to someone, and I feel so ashamed and upset. I am so sentimental when it comes to my own stuff, so I never break my own stuff, but I fail to understand when I'm in a black mood that others are sentimental too. So many times I've broken things around the house (doors, walls, garden ornaments, furniture etc etc etc.) and I hate that I do this all the time.
I think I understand where you are coming from. Are there any other stresses in your life at the moment? For me the tantrums have gotten much worse since I started a full-time job, which is just too much for me to keep handling.
Try to pinpoint whatever might be making the tantrums worse or more frequent, and try to explain it to someone who will understand. I know this may not be easy to articulate your feelings, it certainly isn't easy for me anyway, but just try.
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THINGS I LIKE
Parasaurolophus, Plesiosaurs, Dinosaurs, Pterosaurs, Music, Tuna, Chocolate milk, Oreos, Blue things
Parasaurolophuscolobus. Parasaurcolobus. Colobusaurolophus.
....And Nunchucks are my friends.