That tallies with what they say at http://en.wiktionary.org/wiki/Freund#Usage_notes -
Freund and Freundin may refer to either a platonic friend or a boyfriend/girlfriend. In general, "mein Freund" (my friend) refers to a boyfriend, whereas "ein Freund von mir" (a friend of mine) refers to a non-romantic friendship. Similary, one might refer to "meine Freundin" for a girlfriend or "eine Freundin von mir" for a non-romantic female friend.
"mit" takes the dative. The dative forms of "mein" are meinem (m/n), meiner (f) and meinen (pl). As "Freund" is masculine and singular, this must be meinem.
Your "meinen" would have been correct if the English had been "I am speaking with my friends", but would have to be with "Freunden" as the dative plural form of the noun - Ich spreche mit meinen Freunden, I think.