I personally would lance it with a sterile blade or needle. I have done it with my other animals, they aren't happy but it works. If you take and soak her in warm water it will soften the skin and make it less painful for her.
What I have done with abscess in the past is,
1)Wash the outer area with nice warm water and Hibiclens. (Available in most pharmacies, may have to ask for it) It is a great antimicrobial wash, hospital surgical grade.
2) Remove any feathers that will poke into the wound that could cause more irritation or infection.
3)Lance it and flush it with sterile saline. Here is some directions from Phoenix children's Hospital on how to make sterile saline water.
4) I would pack the wound. When you pack wounds you place some sterile gauze into the wound. This allows the wound to heal from the inside out. It will absorb any infections drainage, then when you change the packing it will remove any yucky dead tissue with it. It also prevents the wound from sealing up causing another abscess. It is a long process but a more sure process. Wash your hands throughly with the hibicleanse before packing the wound. Use sterile gauze.
Whether you should wet the packing with the sterile saline, or just dry pack it, I'm not for sure right this second. There is an old adage about when to use wet and dry packing. I'm thinking it is a wet wound dry packing.
5) A course of antibiotics also. I had one Roo develop a NASTY infection from a dog bite. Took up half his body, I just knew he was going to die. Within 5 days He went from literally green infectious skin to happy healthy bird that Is a beautiful good rooster, who also possesses the fast feathering traits I need for feather sexing birds. This bird was attacked by a stupid Boston Terrier and the wound wasn't big enough for me to pack, plus no one told me about it for a day or so. I was MAD. But with cleaning the bite wound with Hibicleanse removed what scabbing was there, let what could drain. But it had turned into Cellulitous and the infection was everywhere, I used some Augmentin we had for humans here at home we used 200mg crushed up diluted with 3 cc's of water. . And the little guy got his own play pen and discovered TV. It was so funny he would perch on the side of the play pen and scream till we turned on the tv. It was so funny. Here is pics of DLs infection and wound recovery. She can recover just be prepared to a long recovery. If you don't want to go through all the steps I would recommend putting her down. It would be unfair to make her keep going through that pain.