is this cheating?

i caught my boyfriend messaging a girl over snapchat. he said he found her on a message board where people can role play and talk through their fantasies. obviously i’m really hurt and upset by it, but at the same time we haven’t had sex in a little bit, my mental health is at an all time low and so is my sex drive. would you consider this cheating? i know i should probably be really mad at him but for some reason i still love him, but i can’t trust him right now. any advice on how to trust him again?