Omg! I know exactly how you feel and I would be livid too :/
Do you know if he actually used and messaged other women using the tinder account in an inappropriate way? My guess would be that he did, considering he purchased Tinder Gold, but if he did it's obvious that he didn't respect you or the relationship enough to think about what he was doing- and I'm sorry about that.
I think you guys should talk about how the both of you honestly feel. Try and see why he felt the need to do those things if he was in a relationship with you. If he apologises, try and see if he was actually genuine or if he was using an apology as a solution to finish talking about the topic.
I'm sorry this happened to you. <3