I got hope for this one.
A woman that looks like Charlize Theron or Catherine Heigl has a kid that looks like a young Dylan Minette and starts dating a guy that was secretly living in their house the whole time. My guess is early 2000’s like ‘06
There is a scene where the guy has a gun to the moms head while she is driving, she has her seat belt on and he doesn’t, so she just hits the gas then breaks and he goes flying through the windshield.