How do I heal from.............

[Spiritlite]

I have no children, and my husband and I don't ever plan on having children. Mainly because we're too old LOL (I'm 35 he's 40) and neither of us have ever wanted children (I met my husband 7 years ago) and we're both too independent and nervous to have someone depend on us entirely.
So we have cats
And our cat's are our family and our children.
Last year I lost my boy Speye whom I had for over 12 years, he and I were great buddies, every single time I would feel depressed no matter where he was he would hop in the window and lay near me. He was found out on the field dead, I feel from cancer because a month before he died he was on me like superglue and deep down I know he was saying goodbye to me, in fact I told Dan "he's going to die on us Dan he's saying goodbye."
Then our Smudgie cat who was dumped at our house and we took in, and we had for three years, died from Pancreatitis four months ago. A month later we decided we would take in a kitten, a barn kitten, well last month, we found out she had feline aids and that same week developed FIV so badly we put her down at four months of age.
Then our Mama cat, last week we put down becuase she was having seizures every 4 hours and the vet suspected a brain tumor. She was all of 18, we adopted her seven years ago from the SPCA a day before she was to be put down.
My question is...how do I heal from these babies losses. I cry a lot over them, I miss them so much. We're down to two cats now both young and healthy, and in due time we will adopt another cat that is in much need (that's just how we are) or we figure some in need cat will find it's way to our home.
How do I heal from these babies passing? I've only dreamt of my baby Speye, and I feel them around me a lot.
But how do I grieve them? Sometimes I wake up crying and i know it's because i'm grieving my four legged friends
THanks
Spiritlite