Should I stay?

TL:DR : My boyfriend is sexting others, what do I do.Ok. So my name is Nik. I'm 18, and I'm in a relationship with someone who we'll call Tom. Tom is 23. Tom is my first relationship ever, and It has been 2 years and we are still together. Ever since I started dating him, he has been caught multiple times sending nudes to other people in order to be able to mastrubate. Every single time that I've caught him, he tells me it's only for masturbation purposes, and nothing else. He tells me he loves me, and he loves only me, and that I'm very hot, blah blah blah. Very very recently, I've caught him doing it again, after I've asked him many times before this incident if he still does these things, and he tells me no, but I still catch him doing it. Right now, I've been thinking for weeks what I should do. I really, really, REALLY love this person, and want to stay with him. But I don't know if this is healthy for me to keep up. We have a healthy sex life, And never fail to satisfy one another during sex. But he still continues to sext other men, and I don't know what to do right now. What I'm looking for I guess, is, what would you guys do? What are your opinions? I really need help through this and will appreciate anything. Thank you.