Then, calmly and professionally make a note of the areas that need improvement - and notes to yourself on how this might be accomplished. This should help put you in the mindset of revising, rather than defending your work.
1. Opening para needs work - can I introduce the character straight away involved in some action which will show the reader who they are rather than tell them?
2. Mrs. B is too cliched - maybe I should model her more on Aunty May - give her A.M's mangy German Shepherd rather than the spinster cats? She could walk past the local school muttering to it. Kids think it's called Adolf? When really it's Alf?
3. Middle section needs more action - think about it, but there are possibilities to use the best friend situation more. (Or the breakdown in the marriage?)
4. Ending too weak. I'll think about that. Is it too throw-away? But what I emphatically don't want is a too-neat, every tied-off ending. It might be weakened by other problems - partic. the middle section. Leave this revision to last.
Part of being a professional writer is being able to distance yourself from criticism and the editing process - it's not personal. Any critiqueing, whether it's from an editor, a workshop group, a writing tutor or a friend-reader should be about making the work itself stronger. It's one of the hardest lessons to learn, but if you can learn it in your apprenticeship, it will save you from appearing unprofessional. The golden rule in publishing is, of course, never reply to a review unless they actually have a fact wrong - and even then, think a long time before you send the email! Too often you'll simply look whingey at best, unhinged at worst.