AITA for introducing my boyfriend as “my brother” to my ex?

I recently got back together with my ex after being separated for a year and half. During this time I met my current boyfriend. Now I know what you guys are gonna say but hear me out. My ex was the one who cheated on me, not the other way around. <br><br>Now, my ex has been trying to get back with me for a while and I got tired of him calling me baby, sweetie, etc so I finally introducing him to my bf by calling him my brother. Now, I know it’s not like a traditional brother but I wanted my ex to know that he has no romantic relationship with me anymore so I introduced him to my now boyfriend as my brother. <br><br>My ex was livid and started calling me names and stuff but I stood my ground and said I was just trying to set the boundaries as he won’t stop. I told him that him calling me baby, honey, etc won’t change the fact that he cheated on me and I’m not his anymore. At this point my ex told me “wow, you’re seriously acting like a bitch. You seriously think I care? I was just playing with you and you seriously think I care about getting back with you? You’re seriously too cocky for your own good” <br><br>I don’t know if I was TA but my ex made me cry and I haven’t cried in a while so I don’t know what to think<br><br>EDIT: I realized most people are confused about the title. I’m no longer with my ex and was never ever cheated on by my current boyfriend. I was in a relationship with my ex but we broke up and I was single for a year and a half before getting into another relationship with my now boyfriend. <br><br>As for those saying I was TA for lying and stuff, my ex literally called me a bitch,-am I supposed to let him talk to me like that after he cheated on me? I simply introduced my boyfriend to him as he was acting like he still had feelings for me and he was still referring to me as his ex girlfriend etc. <br><br>What’s wrong about my ex calling me a bitch and sending me nasty texts? He called me a bitch and was calling me cocky. It’s okay for him to do that but not okay for me to introduce him to my boyfriend? <br><br>I don’t think I was TA for trying to set boundaries with my ex. He literally called me a bitch after all.