Dont be afraid to mourn and grieve or feel sad......we do have the right, the feelings are real, the loss we feel is real.
And just the same, dont be afraid to move on either....there is no time limit on grief, it is not wrong to grieve more than someone else, nor is it wrong to move on.....it is not a measure of how much we loved someone, or miss someone, by how much we grieve for them.
I remember many many years ago, when I had just lost my dear sister, and I was talking to an old lady, who in her lifetime had lost five of her children, and I asked her how do you cope, how do you go on.....and in her wise, matter of fact way, she said....."you just move on....you never forget....but you do get over it"