Life In 19x19

Thanks, Twitchy Go! By the way,could the large taking of stones in the center have been avoided in some way?What's the wrong move leading to that?

In the general case,what should you do when someone invades your territory?Try to take his stones or try to isolate him? I'm talking about move 101 and move 119 in this game.
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[5.50]TM[1800]OT[5x30 byo-yomi]
PW[Vally79]PB[z2aber]WR[16k ...

Hello. Can you please point out my mistakes? I know I've made some,but I'd like to know them all if possible,in order to improve my play.Thank you.
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Chinese]SZ[19]KM[5.50]TM[600]OT[10x20 byo-yomi]
PW[Vally79]PB[LibertyBot]WR[2d]BR[15k]DT[2013-04-08]PC ...