Regardless of if you have children together or not. DO NOT marry someone if there is no trust, no communication, no love. It won't do either of you any favors.

My partner is dealing with the consequences of making that decision almost 12 years ago, and he and the kids are both going through pure hell right now because of his ex wife.

You'll be better off going your separate ways and co-parenting that way instead of getting into a legal marriage where there's no trust. Good luck.