Hi! I worked for Oracle years ago was laid off, seen all of this before. Been there done that.
Oracle does mass culls and purges very regularly, sometimes more frequently or aggressive than others, but it's the way they have always run the business. They also tend to cut aggressively when they do cut.
As for how to deal with it. If you've just been laid off, don't look back. Let go. It's gone. Focus on you and the future and think very broadly about what your skills are. Oracle likely had you fixated on some small things which really narrows your perspective over time. Don't think about going back unless you become desperate for money and just use it as an interim step. Never try to make sense of what they are doing, why they are doing or what just happened to you. You will go crazy.
For the people who are there, unless you're VERY senior, look outside the company. There are a lot of interesting things going on, and certainly better paid.
I was laid off years ago. I didn't want to go. I was "happy" but a better word was complacent bordering on lazy. In reality I was being underpaid, not appreciated and wasn't enjoying it. It's now worked out a LOT better for me, but make no mistake, it was unnerving, uncomfortable and unsettling at the time. I look back and wish I'd left years earlier. Other people had this same advice but I couldn't bring myself to leave.
Oracle treat employees like abused animals because they can. They know there is no shortage. Their business model allows them to do this financially and the law allows them to. The only way not to be exploited is not to play their game.
Good luck. I hope you all make it through this mentally unscathed or traumatised.