So both are names are on it. So its more difficult but what can be done
When you use the PRONOUN "IT", you're referring to the Texas Car Title, right?
It's not difficult, it's impossible.
You and she are equal owners in the eyes of the law.
Legally you could go take the car and conceal it.
She could come and take it back, and conceal it.
You've painted yourself into a legal standoff.
You can buy out her interests, by having her sign over her ownership interests to you.
You could pay off the loan, thereby saving your FICO score, but car ownership (and POSSESSION) will still be an issue.
She could also buy out your interests, but she's a deadbeat with ROTTEN credit.
Too late now, but for the future, if a bank won't touch a deadbeat; you're foolish if you do.
There's no good way out of this for you mate, without losing more money.
If you want to save your credit, you'll need to keep the payments current.
You could pay off the loan, and she'd be standing there wanting money to sign off on the title.
This one costs you no matter what you do, but it costs you more if you do nothing.
I almost forgot.
If she goes out, gets all "liquored up" or "methed out" or "weeded out" or "cracked up"; hits a four year old riding her bike, kills her, or destroys some millionaire's Bugatti and kills the rich dude, you're getting sued, too.
If she gets parking tickets and fails to pay them.
If she gets red light camera tickets, and doesn't pay them, guess what?
You're going to get screwed for those things, too.
This has liabilities for your far beyond the obvious.