If everyone will cheat anyways..what's the point?

I have these thoughts as my cheating ex came back...and I feel like I'm spiralling down badly.

If another person in future will cheat again on me anyways why not stay with him and give it a go? Maybe love is like this and that's the reality of it. He already cheated so I might as well stay with him and give him another chance... Otherwise I will fall in love again (blindly) and naively believe some stranger can love me the way I love. It's nuts. And then I'll get cheated on again. And the cycle happens again. I can see cheaters everywhere around in real life and then it also happened in my relationship. Maybe it's all not so serious and I take life to seriously and prevent myself from being happy.