Teufel (gatto) is playing up very badly :(

Some background first:
Teufel has always been an indoor cat, when we moved from Germany to Australia we have such a lovely yard that i would let him out with supervision, one night i ended up in hospital and gatto was let out by accident by a guest, when we came home he was injured in a cat fight, since then he did not want to go out again. This would have been in September.
In May my parents came to visit, my dad believes cats should be let outside, despite me telling him not to let them out, he just let them all roam outside and did not care when they came back in.

Once my parents went back home to Europe, Teufel was only allowed out on the weekends when i would be home.

And then it was mating season around here... a very large tom cat would not leave our yard, he has sprayed all over our windows and front doors and back doors, this aggravated him so much that he had a bladder infection. He was put on antibiotics
A week later he was begging me to go outside. I simply said no and ignored his cries.
He then jumped up on the desk where i was working and clearly sprayed in my face and i got urine in my eye.
Spoke to the vet and he gave me anti depressants and told me not to start them until the antibiotics were done.
Its been two weeks and he seemed fine, until this morning, he started crying again wanting to go out, he has been lucky this week as he was out on the weekend and Monday. I simply said no and he proceeded to spray on me.

I then gave him his anti depressant tablet and now all i have to do is wait and see, but i really need advice.

The cat enclosure is not done yet. he has marked his territory all over the house! curtains, walls, clothes, doors.
I will never give up on him, but i desperately need him to stop spraying.
What if he sprays on the baby once its born?

I feel like he is bullying me, as each time i've said no, he just sticks his tail up and starts to spray!!!

I hope someone has some advice or gone through this before because i am at my wits end

I am the only person he has ever sprayed on, we are often at the vets, they know us so well now.
My attention towards him has not changed the only dramatic change was that my father would let him out without thinking about it and that i would be telling my dad off.

We have had his urine checked over and over again. He eats top cat food from the vet, royal canin ph value.

He is neutered, when he was in surgery last year for his leg they checked him over and there is definitely nothing there.
The cat outside has been the problem with him spraying everywhere. He is double the size of him.

I've had him for 6 years, we went through so much together, it saddens me he is taking it out on me for whatever reason

We are off to the vet now, i will be back with an update.

Well.. we are home now from the vet, he has given me half a bottle of their cleaning product for free, i only have to mix it with water and spray it all over the windows from the outside and doors and porch. he also told me i can wash my walls down with it.

Gail i dont keep the windows open, only because it is winter here!

He got an injection with a different antidepressant that should last for a few months, he was such a good kitty. At the vets, If he keeps spraying next week, then i have to bring him back in and try something else!

He basically is in the shits with something but none of us can work out why.