Christy, please accept my condolences on the loss of your sister. And I do understand the difficult decision of putting your beloved dog to rest. My personal experience with grieving is that being strong has nothing to do with it...you may need to seek counseling so that you are able to express some of that grief. Have you considered a journal? I have found that writing allows me to express my sadness, anger, confusion, pain...after the death of my daughter. There is no right or wrong way to grieve but I feel you must allow yourself to grieve. This website is also a wonderful place to share those feelings; we all share the bond of grief.
Take care and let us know how you are doing.
Sincerely,
Laura