You certainly don't need therapy to deal with a phobia of wanking. You don't have a phobia of wanking. You have an abusive, revolting piece of shit in your life who you seem to struggle to dislodge from it, although god knows why.
Therein lies the issue. Your inability to extract yourself from a monumentally unsatisfactory relationship with a man you don't even like. Not really. Nothing you say about him is positive and yet you feel compelled to stick with it anyway. It's as if you don't think you have permission or any right to do better than this for yourself and you'd rather put all your mental energy into flogging this dead horse instead of giving yourself permission to be free and happy without him.
If you need therapy, you need it for this, not for a wanking phobia.
I've heard it said that before you say you have depression or anxiety and rush off to the doctors, just check that the problem isn't actually your MH at all, but just that there are some really shitty people or circumstances making you feel mentally unwell. The removal of those people or circumstances will very often solve the problem all by itself and there won't be any need for a doctor, or anti-depressants or counselling.
He's an abusive sexual inadequate with a porn addiction and a coke addiction. Keep saying that out loud over and over until it sinks in. YOU. NEED. TO. LEAVE. HIM. He will not change. At least he won't for so long as you continue to stick around and tolerate it. If you really care about him then do him a massive favour and leave him. It might just be the push he needs to sort himself out so he can hopefully be less revolting to the next woman unfortunate enough to get involved with him. But the stark truth is that he isn't ever going to change for you. Even if he pretends he has to get you back, it will only be temporary and he will revert to type because that is the pattern that's been set for this relationship. Him being a manipulative waste of space and you being a doormat. There's no cure and no hope for the two of you. Just end it.
On another note, I think you really need to call the RSPCA about his dog. He's clearly neglecting it and it's had no proper training or routine, poor thing. A dog that creates havoc as soon as it 'gets out of its cage' is an animal who spends too much time in that cage and is reacting to stress and anxiety. You aren't the only one this man is making stressed and anxious.