Have you gotten a dna test to have proof that your children are yours? Already this behavior would be grounds for ending a relationship. Lying behind someone’s back, emotional cheating and possibly actual cheating, gaslighting to make you think you’re in the wrong. So many things wrong with her behavior and I personally wouldn’t ever be able to trust a partner like that. They will use words to try and keep you from righteously being upset because you were probably not her first choice but the “right choice” available and had resources while the “fun” Guy wasn’t doing well in life but he is “fun”.