Sounds like either:

1. she changed her mind and just isn't into you

2. the other guy said yes.

Wow! Ok, first, does he not know most men lose weight easily and most women do not? My mom jokingly complained that whenever she dieter, my dad lost weight. You work on your healthy lifestyle at your pace. Talk to a nutritionist if you can. You may have a food that you think is healthy but is sabotaging your weight loss goals... that's assuming YOU want to lose weight, not him.

Your bf has been ignoring you and wants to have sex with others. He is no longer your bf, he is now your ex-bf and current roommate. Find a new roommate, as your current one is toxic. He doesn't want sex with you, doesn't want to be celibate alongside you, just wants to bang others and have you smile? That is intentional cheating. Move out ASAP

Right, but it is now moot. You can't dump her for cheating on you as she already moved on. It's called 'monkey branching'. You don't let go of one branch until you have a good grip on the next. She let go of your branch. Shake her off and upgrade to the non-cheating type of gf.

Opening the dating app is an intention to cheat. Trying to match with someone is an intention to cheat. Chatting with someone on a dating app is an emotional affair. Meeting them and giving them a hug or a kiss is a physical affair.

Unless she dumped you first... you mentioned she dumped you in the title... and you were only bf/gf, so what does it matter now? She failed the gf test. Find a better person.

Wow. I'd talk to a divorce lawyer. He and his whole family is too much!

Tell him of your insecurities and apologize for going to the club without him that time. Ask him if he would be willing to set a boundary to protect your relationship: no going to clubs or other 'pick up' spots without the other. That way, there's no doubts, no false friends making false accusations of cheating and no people making unwanted passes.

The only part of where he will live that you should be worried about is "not here". He sounds like a dead fish.

As for the pets, do they have a favorite? Perhaps where he goes (or where you go) won't allow pets. TBH, the pets should be the hardest part of the breakup, but don't let them stop you from taking out the trash!

I can read this without the "she kissed someone else" and see a break-up. You are no longer attracted to her in that way.

If you choose to break-up, don't mention cheating or anyone else. Just tell her you are not feeling for her the passion you once did, and you feel the relationship is tired. Would you rather be friends? Can you give her time to move out? The discussion doesn't need to end the living arrangement. You might stay roommates till the end of your current lease (or a month or two after the discussion).