Everyone grieves differently.
There is no prescribed amount of time for grief since it is different for everyone.
Some common feelings associated with grief include denial, anger, bargaining, depression, and finally acceptance, though often there are other feelings as well: shock, guilt, regret, loneliness, and finally hope. Still, because grief is different for everyone these stages don't necessarily go in any kind of order, and they can cycle and recycle back around. Also, not everyone will experience all of these, and each person experiences them in different ways.
Grief is a process.
Grief affects a person physically as well as mentally and emotionally. It can affect sleeping, eating, memory, judgment, concentration, cognition - all of it. It doesn't mean you are going crazy when you experience these things. They are part of grieving.
Griefs, or rather losses, pile onto each other. In other words, every new loss can bring up all of the old losses. You don't know which losses will affect you the most because you don't know which ones will bring up the old losses at the deepest levels.
Telling people to "get over it" is extraordinarily unhelpful.
We don't know what someone else is experiencing in grief, so the best we can do is to walk beside, to walk with, and to listen without judgment. We can't hurry someone else's process, and trying to do so usually results in unhealed and prolonged grief.
It is really important to go all the way through the grief, no matter how uncomfortable that may be, because unresolved grief does not allow us to be the whole people we are meant to be and may interfere with our abilities to risk and trust again in the future.
With all of this wisdom however, the bottom line is that losses hurt. And that while it may seem that we should be able to gain some ability to handle grief better with each additional loss, in fact, because each new loss brings up all the old losses, each new grief can feel like the weight of the world dumped onto us once again. Each time a major loss (or any loss for that matter) happens I find myself wondering if this is the one that will completely destroy me, if this is the one that I simply won't be able to get through, if this is the one that is just plain "too much". And all I can say is that, like with everything else, we are called just to take one day at a time, sometimes one step at a time, one breath at a time.
Remember that you don't walk this alone. There are people here to help. There are people here to care and to offer love and support. There is help when it feels like too much.