If Ding Wugong could capture Yang Xiaoyun, naturally it would be best to take her down.
Unfortunately, he ultimately underestimated Yang Xiaoyun's martial arts.
Not to mention that he is currently suffering from severe poisoning. Even in his normal condition, he is no match for her.
Thus, after one move, realizing he couldn't capture her, he harbored another thought...
He wanted to die by Yang Xiaoyun's hand!
He knew that if he wanted to kill himself, he probably wouldn't be able to.
Su Mo wouldn't give him that chance.
As for whether Su Mo would mercifully provide him with an antidote?
He never even considered that possibility.
The reason he had been compliant until now was only because he was waiting for an opportunity.
Yang Xiaoyun's appearance was his opportunity.
If he couldn't subdue her, then dying by her hand became the best way for him to escape the agony of the potion of separation.