I'm about to marry a righteous sister, but I struggle with an addiction to haram content. It's decreasing and I hope marriage will end it, but I fear relapsing afterward, which would be oppression towards her. Should I still go ahead with the marriage?

Marriage is from the remedy, and Imam Ibn Baz said that whoever has desire and fears for himself must marry. Make your repentance sincere, cut off what leads to the sin, and never tell anyone about your sins that Allah has covered. Replace the habit by busying your time rather than only trying to quit it while having lots of free time.