She said she doesn't like him as she thinks he is trying to hard and thinks he is funny and that I act different around him (I don't)
Your quick dismissal of her opinion won't help you here, op. Why does she think you act differently? I was 15 when my mu got with a man after cheating on my dad with him. She was different with him, VERY different. But she wouldn't accept it. She drifted even further away from me once he moved in (we didn't have a great relationship to start with) & it caused such a huge divide, we have spoken since I left home, over 20yrs ago. The ironic thing? They are no longer together. So she ruined what was left of our relationship, for him, for nothing.
You cannot see yourself how she does, when you ate with him. Ask he what it is that you do.
Trust her instincts too.
and he wants to be a family in the future. and you?
And everything oikopolis said @ 19:21:23 and again at 20:24:20
Ive been miserable for their sakes for years LOW, op. I assume by this you mean, because you stayed with their father? You make it sound like you had no choice, like they forced you into doing what you didn't want to. And they didn't! I hope you don't say that to them. It is NOT their fault you were miserable. Not at all. How dare you blame your children for your misery!! You obviously resent them, op! This is very unhealthy!
In the minds of adults it might seem quick, but bear in mind how long the 6 week summer holiday felt as a kid! Oh please! The child is unhappy, she is 13 & does have some concept of time. Like her father left at the beginning of December & her mother started dating this guy just before Christmas too & introduced him very shortly after. Don't patronise the daughter because you think she has no time concept. MY 5yr old understands that period of time.