Tell her you meant to text her that you hate someone else, but you just got mixed up because phones are so hard!!!
A good old, “OMG I meant to text you that I hated Jen, but I totally texted you that I hated you! LOL. OMG. I AM SO BAD WITH PHONES!” should smooth over the situation 90% of the time. Remember, Sharon totally sucks at phones, too (she once asked you how to “uninstall” a photo she took), so you’ll probably be finesies.