The speaker looks back on a relationship that someone else treated like a game. At the start, the other person promised it would be fun, but the speaker ended up with toyed-with feelings and a broken trust. The repeated word "played" does a lot of work here: it shows how the game was set up by the other person, and how the speaker got pulled into it anyway. "I played along" sounds a little embarrassed, as if she knows she let it happen.
Then the poem shifts. "Now I'm better" can mean she has healed, but it can also mean she has become better at the game than the person who started it. The last line is a sharp, almost taunting question: "How does it feel to lose to a girl." There's no question mark, so it lands more like a statement than a real question. The mood moves from hurt and quiet resentment to confident, cold satisfaction. The speaker is no longer a victim; she's the winner, and she wants the other person to know it.