Sharing Our Innermost Thoughts

Should I leave her or not?
Actually 1 year back i met a girl after my first breakup. And i really feel nice around her, the vibes were matching, soon we started meeting on regular basis and our bond grows. But at time she was with someone ( not in a relationship but they both have just confessed there love and i m not sure weather confessing love ties you in a bf gf relationship or not) after knowing that she loves someone else block my love feeling for her coz I know if this goes out it will definitely affect the friendship.
One day her partner goes abroad for masters and after that we start spending more time untill one day when I was out of town, i was literally feeling low and was like I m missing someone much deeply. And the next day she texted me that’s she love me.
At first I thought she was in good mood but later on when I come back and had conversation with her ,it was confirmed and for me it was Glory that’s the girl whome I love has confessed her love with me but i was confused that how could this be like she is with him and still loved me.
And one day at my place we get close and it was like we both found the missing piece of our puzzel life. We both cried so much while making out.
And never thought that this could be happened.
Now she is gone towards her masters courses and i m afraid that what if we. Both don’t end up being together?
And i get some nonsense thoughts in my head that she was just using me here and all.