Hello from Prague

Hello,

we live in Prague, I'm Czech, husband is British and we have an 8 year old daughter with high functioning autism. Initially she was moderate but with age she is now high functioning. She can be very moody and downright horrible, telling me things such as that she will kill me and that she hates me and sometimes pinches me or hits me. The problem is with me not being able to handle her when she starts acting like this and so I tend to get hurt and offended by her comments and behaviour which then leads to a difficult relationship between us because I then become horrible back. Somehow my husband is able to raise above this but I can't seem to. It's as though she triggers my own childhood traumas and I end up feeling helpless and very angry with her at the same time. Is there any book or do you have a way to deal with overreacting to your child saying hurtful things? 

I just don't know how to handle her behaviour and feel its getting worse. We tried penalising her, didn't work. Then we tried the positive approach of "we know you don't mean to say/do these things" which she tends to react better but eventually I lose it with her. Sounds like I need more help than she does....

Thank you for any tips!