[20/m] A girl that I love [20] is back in my life after years of not talking...

Ok, so about a month ago I got out of a serious relationship of 2 and a half years. But before that happened, about 2 months before, my "ex" (we never dated, we were just in love with each other) adds me on instagram. This threw me off like you wouldn't believe, because we hadn't talked in years. I'm in my third year of college. The last time we talked was junior year of high school, and through out high school we would always come in and out of each other's lives. After Senior year, I thought we were done with each other for good. Anyways, after she added me, I realized something: I STILL loved her. I thought I had gotten over her, but apparently all I did was just bury those feelings deep inside me. I didn't let it affect my current relationship at the time (or at least I tried not to let it). Anyways, my ex starts liking my pics and commenting on them, but I don't think too much of it. I was in a relationship, and even though I still felt this way towards my ex, I was determined to carry my relationship with my current gf through because we were faithful to each other. Fate had different plans because we ended up breaking up, for completely different reasons though. I never saw this as an opportunity to get with my ex...I had just broken up with my gf, and my ex, i think, is also in a serious relationship. I'm not entirely sure, so i don't know. Anyways, one day she ends up inviting me to church. Me and her are very serious about God, and at first I thought it was a bad idea...but she kept inviting me so I eventually caved. I've been recently attending her church, and man, it's like those feelings never left...we're not talking much at all however. She doesn't seem interested in catching up or re-acquainting herself with me. We'll say hi and hug each other and talk for a minute or two, but that's about it.Idk how she feels about me...she used to tell me she loved me so much back when were in high school, and she was actually the first one to tell me she loved me...it's like I'm back in 9th grade again lol. It's all so weird, maybe we haven't talked much because we haven't warmed up to each other like that yet?? Or maybe she just doesn't care anymore?? But why would she invite me then??oh Idk, I'd like to know what you think. Tell me straight up, idc tbh. I can fill you in with extra info, I just don't want to make this too long lol.