My mental health is not good for this right now.

An old friend of mine has recently come back into my life telling me that he loved me and wants to be with me. I have a partner of nearly 4 years ttc for nearly 2, I dont know if it's me or my partner and I'm scared no matter which way. And now my brain is frazzled! Until about 10 mins ago when he told me he wanted to leave his wife and 3 children for a life with me. Help help help!