You use considering that to indicate that you are thinking about a particular fact when making a judgment or giving an opinion. Considering that you are no longer involved with this man, your response is a little extreme
When you are giving an opinion or making a judgment, you can use considering to suggest that you have thought about all the circumstances, and often that something has succeeded in spite of these circumstances. I think you're pretty safe, considering
You use considering to indicate that you are thinking about a particular fact when making a judgment or giving an opinion. The former hostage is in remarkably good shape considering his ordeal