Young dad, with the babys mum, but there's another girl

i am a young dad, and i am in a relationship with her mother, we have been together nearly 5 years and recently theres another girl. i met this girl at work, and we just get a long very well, we are similar in some ways and different in others. she just seems different to any girl i know, im never not smiling when im with her, i just dont know what to do, any advice at all, please?

Really? it is very easy to get along with a work colleague who has no responsibility to your child, or has to put up with the day in day out grind of having to put up with your immaturity, I promise what you will do is come off second best, especially when you have to look after your child when it is your turn, and work colleague is not that interested in that other girls baby. good luck with all that. If you are not happy in your relationship then man up and leave, but do not cheat and lie and then ask for help on what to do.

Don't be a fucking idiot man, cheating or looking to cheat is not the way. I am praying the price for this as my partner of 5 years is moving 130 miles away with our 2 year old daughter. Sort your act out for your child.