Is bitch too strong a word?

It's pretty strong and implies aggressive, hostile behavior. Only you can decide if that meets your situation.

As female dogs are call bitches and most dogs of either sex are kind and loyal and loving creatures I had always had a hard time using it as an insult.

I had known any numbers of women that comparing them to dogs would be way too kind<grin>.

Bill, there are many many many words in English that are spelled the same and have the same pronunciation, but have different meanings. This is simply another one of those situations.

As Engineer noted it is pretty strong, but its strength depends on a number of things. Good friends might use these often, but they know when and how to use them, example, right intonation, right timing.

When used with strangers and people who aren't really close to you, they would invariably be taken as major insults and timing and intonation wouldn't change that much.

In what format would you be using the word? In a letter to an editor? Yes, its too offensive. In a letter or email to an employer, your work supervisor, or some agency of whom you are writing a complaint to/making some sort of appeal to? Yes. Find a more sensitive way of describing the situation to make your case.

In a water cooler gossip session? Yes and no, depending on how much you trust the person in which you are confiding the information to.

While ranting to your best friend during coffee time or lunch? The best place to use such language, still I would refrain from using it without proper and reasonable elaboration.