About to be married.. am I doing the wrong thing?

You can do this. And you are very normal. This is such a pervasive issue in our culture that it is very common. So please do not feel like you are alone, that you are out of the norm, that there is something wrong with you, etc., because none of those things are true. We all can relate in one manner or another. You do need to do the hard work now though to rid yourself of this poison. And think of it like that; every time you go to porn and masturbate, or masturbate with the fantasies you have gleaned from your porn use, you are taking a poison into your system. It will harm you! You don't want that, and you don't want the residual effect it will have on your future spouse and on your marriage. Notice I didn't say the effect it may have, because I don't believe it is may, but it will have an effect. Even if you're trying to be good about it and refraining from PMO and having plenty of sex with your new wife, I guarantee you somewhere sooner than later, it will rear its ugly head again if not addressed now, and then it will deeply hurt your relationship with your wife and potentially erode all trust. You do not want that to happen. I am just one small example in here of someone who let that happen and then has worked long and hard in an arduous uphill journey to recover that trust and relationship. Please take care of this now. I wish only the best for you and much joy and blessings in your upcoming marriage. I happy to help in any way I can so feel free to reach out if I can be of assistance.

 

I agree with what @Robindale has written.

If you can be upfront and totally honest with your wife-to-be then you, my friend, are on the right track IMO. I personally believe you can do this! You can get a grip (no pun intended) on your addiction. Just don't keep secrets from your wife. If you do, you don't deserve her, imo. She's putting her life on the line, she's saying - 'you're the one and only I want to give my everything to.' Respect that.

Be aware that you are taking dirt into a clean marriage. It will be your responsibility to clean it up, not your wife's responsibility. If she sticks by you then you are a very blessed man.

Anyways, how's things going? How many days until you are married? Excited? I'm excited for you!!

 

You're doing the right thing by coming here, it's an important step in fixing this, and it IS fixable. She will find out, the longer you wait to tell her, the worse it's going to be. She's counting on you, you're her future husband and future father of her children, you can't hide something that affects you this much from her.
Talk to her, b honest, and keep coming back here.