Sensitve to comments about my accent lately

Haw, I don't think she was REALLY meaning it... but I didn't have a clue how to respond. I felt awkward.

It took me a while to overcome the "Why on earth would you marry a Geordie???" jokes I used to get from the southerners.  I took offence for a while, but would just smile and say "Because it was the best thing I have ever done!" or sometimes I would just chuckle half-heartedly and change the subject.  It is awkward when someone makes a joke you don't particularly "get" which could be taken as an insult, especially if the delivery is dry, but just smile and shrug it off.  That's what I do!  There are plenty of times people make jokes I don't get, to be quite honest, I just smile and try to pretend that I know what's going on, then ask DH about it later!   

Haw, I don't think she was REALLY meaning it... but I didn't have a clue how to respond. I felt awkward.

I wouldn't have known how to respond either. I would probably just have given a little fake laugh or something.

I'm not good at insult humour; I'm always afraid I might accidently hit a subject that is sensitive for that person, so I won't insult someone even as a joke. (For example, what if your husband had spent a large part of his life being teased for his looks and as a result had spent loads of money on psychiatry and plastic surgery.)

I once went to visit the home of a woman I met in a dance class in the US, where I met her boyfriend and some of her friends, and all they did the whole time was insult each other - what I would consider to be really nasty insults - the kind of thing that I would hold off saying to someone in a fight because I would be afraid of regretting it later.  They obviously got along and didn't take it seriously (otherwise they wouldn't be friends and she and the boyfriend would've broken up a long time ago), but it was just very strange and uncomfortable for me.

I once went to visit the home of a woman I met in a dance class in the US, where I met her boyfriend and some of her friends, and all they did the whole time was insult each other - what I would consider to be really nasty insults - the kind of thing that I would hold off saying to someone in a fight because I would be afraid of regretting it later.  They obviously got along and didn't take it seriously (otherwise they wouldn't be friends and she and the boyfriend would've broken up a long time ago), but it was just very strange and uncomfortable for me.

Awwwwwwkward!     That sounds awful. 
DH and his friends always make fun of each other's hair and clothes, taking "the piss," really.  But, no one here speaks to me that way.  I suppose they know I might take it the wrong way or get my feelings hurt.  But it's just the way everyone is around here.  I must admit it is a bit funny to hear my MIL taking the mick out of my FIL for having a comb-over!  But I would never tease him about it.... well, to his face!