I doubt sharing a bedroom will get you into trouble. Your ex can file to modify custody and visitation but I doubt he will be successful based on...

What can I do if my ex isn't very supportive of my relationship with my kid?

I would first start with dealing with the visitation. Maybe a Motion to Enforce or a Motion to Modify. Get an attorney.

Can a police officer take my tag off vehicle and make me pay all fines before getting vehicle out of impound?

Yes they can do it and even f they couldn't, they are gonna do it.

What to do next and what to expect!?

Hire an attorney to help you with the supervised probation violation.

I already answered this question. Duplicate question.

Can I be thrown in jail if I'm paying a fine and warrant in full?

You should be able to just pay it and get the warrants released.

You can expect that they may take your kids into custody. DHS is a nightmare and you don't want to deal with them alone. Hire an attorney.

Can a step parent petition for adoption against their spouse and the non custodial parent?

Seek an adoption attorney. Thenare a lot of unanswered questions here.

Plead not guilty to in city court to petty theft case of a $24 pair of earrings

Hire an attorney and seek a deferred sentence to keep this off your record.

Other resources other than OK Legal Aid & Trinity Legal that I can find a pro bono attorney for civil family issue?

Call around and get pricing. Many of us offer payment arrangements.