I had a wet dream due to fantasizing to much, does it count as a relapse?

I would say no. This is about your conscious decisions not to watch porn. This dream is involuntary, ok so you did fantasize but I'd say that's a lesson learned. Also I think there's a big difference between fantasizing about P or real life (the latter being natural).

 

What color was the semen?

 

No, a wet dream is not a relapse. There are no more what-ifs or why-nots to discuss on this. A wet dream is simply a bodily function.
As for the colour of the fluids, that could do with the fact that it is old, built-up fluid.

 

Wet dream is not an relapse, but don't fantasize and watch out for the chaser effect.

 

Quality of the sperm is actually improved over time. Other than that, there are no what ifs indeed. It's not something you can control.

 

Yellow? Wonder why it was that color? urine?

 

You gotta push through it. Don't worry, this is only the first wet dream, as your body gets used to this new intense release, the relapse-like after effects genuinely go away.
Just take your time with things right now. And just don't give into urges.