HELP please

[Mommamouse]

My ex fiance/baby dad have been broken up just over 2 months and I've just found out he's already living with another woman and seems to have been having a thing with her for quite a while. He doesn't know I know about all this however and he has put son most weekends.

Am I over reacting thinking this is so far beyond acceptable to have this woman in my son's life and not even be told and not to mention it is way way to soon anyway

No you are not being unreasonable.

No you're not necessarily being unreasonable but unfortunately there isn't much you can do about it other than be an adult and try to talk to him about it and the impact it may have on your son.
Put any feelings of bitterness to one side though and focus on your son and what's best for him. How is she with your son?
My exH introduced our kids to his new partner the day he moved out of the family home - albeit under different circumstances; I'd ended the marriage and we'd been living together but separated for around 6 months during which time he'd met his new girlfriend. At the time I wasn't happy about it purely because I felt he should have time with just him and the kids before introducing anyone else. Saying all that, 3years later they're engaged, my kids love her and we all get on well. It doesn't have to be a terrible drama but it depends entirely on their relationship as to how this will work out. Unfortunately you have no say or control over that so concentrate your energy on giving your son as much stability and security as you can from your end and being there to help him understand as best you can.

Of course you are not unreasonable to be very concerned and upset. That said, you have zero control as to who your ex is in a relationship with. If it were me, I would swallow my pride, and for the sake of my child, I would do my best to get to know his new partner. She might be a lovely person who will be kind to your child. Making things a battlefield will benefit no one. Your relationship with your ex is over, so I suggest you be the bigger person and do your best to make things amicable.

I completely understand what your all saying however I have said to him a number of time for the sake of our son (who is only 16 months old) that if either of us find a new partner that out of respect to each other we should inform the other and make sure that its a serious thing before introducing them into our sons lives. He's lied to my face about this and has hidden everything and so that's broke my trust when it comes to him doing what's best for our baby.