((((WePow))))
This is a difficult one. In principle, it can be incredibly enpowering to confront one's abuser, but this also really depends a lot on the details of the specific relationship - which I know little of. Do you know what you want to do or say when you meet him? It is often the case that perpetrators are in deep denial so I'm not sure if you can expect him to just realise the enormity of what his actions did to you, without you actually explaining it to him. I doubt he is aware of mental health issuesin general, to be honest. And even if you explain, he will probably show disbelief and deny it. Don't be surprised if this happens - it might actually feel like an anti-climax in the end. So be prepared for that too.
Also, he is your father, so while I'm really not worried about how this encounter will affect him, I'm concerned about the effect it will have on you, whatever happens to him as a result of this meeting. Also, I imagine it will create some turbulence in the family - what impact will this have on you? These are just points to think over. It would all be very different if he was just some odd guy who abused you; the fact he is your dad might complicate things more as to the effect of this on you and the rest of the family.
I'm glad though that you seem to know what you want to do and have discussed this with your S/O. Can you also discuss it with your T once again? I know he advised against, but once he realises that you are determined and it's your decision I am sure he will give you some useful further support towards how best to confront him and what the most effective, safe and empowering way to go about this would be. I think calling your T and asking for an appointment before Weds would be a good idea at this point. I hope you can work out a way that can help this encounter contribute to your overall healing.
Good luck with it, in any case.