Hi B111,
I dont think anyone can answer that categorically, but my husband has cheated on me a few times, always when he has been using Coke. Its not an excuse, but it could be a reason.
Honestly, being with a cocaine user is like being on a life rollercoaster, and living with Jekyll and Hyde, so its quite possible that it could be the reason.
If I was you, i’d certainly not rush into the wedding until you have rebuilt trust, and that will take some time.
Sending hugs