Pregnant and scared to tell partner

I was thinking of writing a note(we've always wrote notes throughout our relationship and he will leave them on my car for when I finish my late shifts at work soo) to him telling him that I'm pregnant and that i understand that it's not what he wants for his life and that I don't want anything from him but I'm going to raise this baby alone- with the help of my family and friends. Not sure if this is too immature? I was just going to get him to meet me at the place we first met and give it to him then leave. 

Any other ideas? I love him so much and I really don't want it to end but I totally understand if he leaves me because of it.