when is the right time to quit with my lover?

SooooOOOooo, i split up with my boyfriend 2 months ago, and my friend helped me through it. My friend is male and was originally emotional support, but things got frisky one night, and now we are, i believe the term is '**** buddies'. Ive met someone knew, its really early days, but this new guy is just perfect for me, and we click like mad, and i know he is interested in me, so im thinking this should go really well. i dont wanna cheat on him, which atm im not, but will i know the point where i am cheating on him, or should i own up and say tell me when you want me stop? or just trust that i will know. This new guy is really old fashioned we went on a date the other day and he wouldnt even kiss me yet, wants to wait till its right and romantic.

Do i tell him whats going on with my friend

Do i leave it and hope its guna become clear#

Should i wait till our first sexual experience together before i stop with my '**** buddy'

Advice please

BTW i am 22 and perfectly legal to do the dead :D