Is this considered harment? please help!?

ok, my fiance's ex/babies momma is sending me a bunch of nasty messages and now she's got her friend sending them too. well i haven't replied to any of them cause we are going to use them in the custody battle. well, they are calling me names and talking bad about my daughter and talking bad about my fiance. so here's my question.... can i get then for harment or even slander?what do i do ?