I need some advice

Me and my ex broke up about 4 months ago and we were together for about 5/6 months. His last words to me were "well yeah, gotta go" and I have not talked to him since..... I've reached out but I stopped when I started to realize that he really didn't care about me. Do you all think he really cared about me if he ended the conversation like that and haven't talked to me since? I just really don't think he actually cared about me based off how he did that.