الجواب وبالله التوفيق
It is a severe sin and an extremely abominable action to leave salah on purpose however by doing so the person does not become a kafir(disbeliever).
However by stating “mai kafir hoon” constitutes kufr(disbelief) thus your husband has become a kafir. He should perform istaghfar, repent abundantly, renew his faith in Islam and renew his Nikah with you.
وفی الھندیہ –مسلم قال: انا ملحد، یکفر الخ (فتاویٰ عثمانی، ص 88، ج 1
واللہ اعلم بالصواب