You know what's going on, and it isn't good. A tattoo doesn't prove anything... Johnny Depp got a tattoo that said "Winona Forever" back in the '90s, but now he's happily married to somebody else and had the tattoo changed to say "Wino Forever" as a joke.
Tell your boyfriend how you feel about the text messages. If he truly cares about you, he will stop texting these other women and treat you right. But let's be realistic, if he really cared about you, he wouldn't have been texting in the first place. He's a selfish jerk who is just using you. I recommend that you dump him.
Good decisions come from experience. Experience comes from bad decisions.