There are three groups to care about:
1) Your O4 group which is threatened by a cut at O6
2) Your H5 group, which lacks eyespace, but is out in the center
3) His D13 stones , who have lots of Aji cause of the F12 cut
So there are two main alternatives for me:
Defend the O6 cut at maybe N8 or Defend the F12 cut to make the capture of his two stones more likely and give your H5 group something to run to.
Some questions to assess the situation
What is more urgent ? - I'd say the O6 cut cause if it's sucessfull your shut off
What is huger? - The F12 cut gives a nice moyo, but it's not definite, the death of your whole group at bott would be more definite territory.
Can the O6 cut be outmanouvered '? - Maybe you can surrender some stones with N7 and if he connects N8.
So Ill play F12 and try to sacrifice some stones at bottom.
Another idea is to keep on attackin his middle group and secure the cut with something like M8, The idea here is just to get time to play F12 as in the attack, if he answers, the O6 cut is secured. But it's no real attack in my eyes. As black i would then start something with my two stones at D13, maybe invade the corener or try to connect outside or both.
P.S.
Maybe M9 is a better attack, but thats too complicated for me right now

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