Of course it is completely outrageous that Richard can contemplate Anne wanting anything to do with him at all. It exemplifies the power the character has in his words, how he is a master manipulator of vocabulary and how single minded he is. He is also someone with a longer term plan: "I'll have her, but I'll not keep her long." He basically turns everything around on Anne, so that everything he has done has been for her, and ultimately surprises himself with his success saying that he will entertain a score of tailors to make himself look good!
This scene was psychologically complicated and confusing. It was completely ridiculous that Richard can win Lady Anne's hand in marriage. He had murdered with his own hands, her husband, the dead Henry VI and King Henry. It is quite hard for readers to comprehend that Anne would wear his ring and let him court her, who had murdered her husband. It is complete insanity!
This shows us that Richard's mastery with his manipulation and distortion of words to deceive people. The wooing of Lady Anne shows us his persuasive talent to a whole new level. His ability to court a grieving and bitter person to accept him as her husband shows us his ability to play with other people emotions and use them to his advantage to overcome their defenses to make it sound so caring and sincere, but in fact, this two-faced wolf is lying through his teeth, which distastes me so much.
He plays around with his words to toy with Anne's feelings by pretending he was sincere and ravishing about Anne's beauty. He said that he killed her husband because her beauty attracted her so much that her husband was an "obstacle to his progress and it was primarily her fault for this tradegy.
Finally, in a highly theatrical gesture, he gives her his sword, telling her to kill him if she would not forgive him as he doesn't want to have a guilty conscience in his life. She stabbed him a few times, but could not bear to kill him. This shows that Richard have a tremendous power over Anne as she cannot backed her actions with words but in the opposite, Richard can backed up his actions with words.
All these shows us that Richard is a master of trickery and manipulation of words and gestures that Anne tried hard to resist but couldn't.