Okay Hamlet dear.
This advice isn’t universal, and parts of it will probably hurt you more than help you, because grief isn’t universal. We all share the human condition, similar experiences, similar emotions, similar perceptions at times, but we all react differently, and regardless of how parallel our conditions may be, we ourselves are not identical. And I think you will be very aware of this, especially with how insolent your mother and uncle are being. It feels like you are isolated and jumbled, and even that your grief is out of place. I assure you it is not.
So the first thing you need to know is that you are not alone. True, no one processes grief the way you do, but you are not the only one who has ever experienced grief. You are not alone and your feelings, frustration and pain and betrayal, are valid, no matter what your parents try to console you into believing.
In addition to this, do not isolate yourself. The apathy and turned heads of others already make you feel alone, pulling further away will only intensify that emotion. I realize you don’t relate at all to your parents now, and likely they won’t be any help to you during this process, but don’t tuck yourself completely away. As humans we tend to try to do things on our own. We try to be strong and hold our own selves together. We try to make ourselves believe that we don’t need help. Don’t try to fake it; let someone in. Let Horatio in. Be honest with him and let him try to help. Like I said before, we all share the human condition and we aren’t meant to weather difficulties alone.
(On this note, I’m not sure adopting an antic disposition is the best approach to this situation, especially as it will likely isolate you further, not to mention threaten your chances with Ophelia. But maybe that’s just me. As I also said, we all process grief differently so it’s your choice. Perhaps you ought to ask Horatio or Marcellus for advice. They have already to sworn to secrecy after all.)
Lastly, I think you should get a pet cat; that way you won’t be alone. Cats are excellent for dealing with grief. They have super soft fur, make great rice bags, and they even purr whenever you spend time with them. Plus, since your parents want you to stop wearing black, spend a little time with a tabby and your clothes won’t be black anymore, problem solved.