Just dropped the last bit of cash I had left on dicing yesterday
Just train stuff to forget that it happened, and sooner or later you will just recoup and move on.
If you still have things in your bank, you could go do things you enjoy to do in RS if you don't like training skills/are maxed total.
For example, I boss a lot. That is something I really enjoy doing in RS. I have all the food/pots left that I need for bossing. But I have no armour/weapons XD.
Goodluck, it sucks but it happens. I haven't lost that much for many years, and you are right there are a lot of ways you could have put it to use. But life goes on.