I'm not going to go on about the age difference as normally i wouldnt care....but as a mother I dont even allow my ex's new partners to have contact with my son and they are/have been much older than you are. I dont know them, i dont trust them and quite franckly, unless he was serious about marrying them then i would never allow contact (and his wife is probably<rightly so> thinking you wont last long term and is putting her children first) add into that the fact you are only 18...I would not trust any 18 year old around my child.
Life is not measured by the number of breaths we take, but by the moments that take our breath away.