As many have said, this isn't a real thing. It sounds like she was trying to groom you. The comment about the other girl wanting to play with you boobs is reminiscent of the 764 group, who are dangerous, violent psychopaths.
Most importantly right now, GOOD FOR YOU for blocking her!
Secondly, you should report this to the cops. Please, PLEASE report this person!
Thirdly, if you did send her more than just a picture of your palm (i.e. and aren't telling us the whole story), don't be ashamed. Groomers are very good and very practiced, and can get past all logical defenses.
Or they're part of a cult/gang like 764. Either way, police should be involved.