Tried not inviting him anymore?

So you're mad at him for jumping in too fast? Or you suspect the girlfriend was around before your mother passed away? Don't judge him too harshly if it's the former. Everyone deals with mourning a different way, and honestly, he's probably feeling lonely after losing your mother, and infatuated as it's been the first time in more than 30 years that he's been free to fall in love with someone new. If he was faithful to your mother to the end, he kept his promise to her, and if he's wanting to move on, you might advise caution before getting in deep on a rebound, but he's not doing anything morally wrong. It sounds like he's going to remarry eventually, and yeah, it's going to be awkward and weird, and if you're still in mourning, it will be hard on you too and you probably need some counseling or therapy. But you can't control his life and dating any more than he can yours at this point, and the best you can do is wish that he be happy. Course if he was cheating on your mom all along, that's a completely different story and likely quite a bit ****** up.

Honestly good on him for moving on quickly, the alternative of moping around for years or possibly forever is far more grim and I'm sure your mother wouldn't have wanted that.

You're 31 and still living with him? Are you sure you aren't jealous?

He deserves to be happy, let him live his life.

You're 31 and still living with your dad??

studies show that if someone was in a happy marriage they tend to remarry faster after their spouse dies furthermore marriage is until death do you part and im sure your mom would want him to be happy so why don't you

this sounds like you are so comfortable you are scared of the change this gf will bring...your 31 you no longer have a say

the marriage could have been over for years but stayed together maybe for kids...so they could have a normal family life.

You're 31 and he comes into your room at night to check on you? WTAF?