My wife had the same strong reaction when I first talked to her about cuckolding and mmf threesomes.
Take it slow. Let her know that it’s okay that the toys are just objects to her. You’ll just have your own fantasies about them being other men.
When you want to introduce her to something new to do with the dildo, like fucklicking or dp or spit roasting, try showing her a picture that depicts it. Do it outside the bedroom so she feels free to express her opinion pro or con without feeling pressure. Be okay with her expressing negative feelings about the picture. Let her know you are just showing her something you two can do with the toy.
Let her know that you are showing her the picture because it excites you and you’d like to try it with the toys. Accept whatever she says and always reinforce that you love her. She will probably agree to some things and you can integrate them into your play. Don’t tell her the toy is another man while you are playing. She will do that in her own mind because of the pictures you showed her.
Don’t spring such a picture it on her in the middle of sex unless you already have a habit of looking at porn during your play. If she has a negative reaction, you don’t want it to be in bed and associated with going from being turned on to being turned off.