Galaxy s5 can't do anything with texting?

recently switched form iPhone to S5, and I transferred all my texts (about 72,000.) There was a warning saying I'd have to leave it open for a while for it to stop lagging, but I left it open all night and, nothing. Can't send, and it freezes every few seconds. I can't open the big thread, and if I do and try and text them, it freezes and crashes. Earlier today I tried to delete it, and it said "deleting" for along time, eventually went away, and the thread was still there. I really wanted to keep this thread, but I decided I could delete it if it meant being able to actually text again. Can't delete. Can't text. I'm a little disappointed. I don't know why I;m having these issues, 72K isn't an ridiculously unreasonable amount.

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