You know what I heard from that massage he sent you? 'Me, me, me, me, me , me, me, me, me, me, me, me, me, me, me, me, me, me, me, me, me'. What about you, user?
Tell him that you are going to see a solicitor because you no longer wish to be married to him. Whether he has cheated or not is no longer relevant because he is telling you that the marriage is over by his actions and his coldness towards you. Anything else he says is just noise trying to justify himself.
Your mental, emotional and physical health will be damaged if you don't end the marriage and your children will suffer through his selfish actions. By divorcing him you are showing your children that they have a parent who is strong and capable and the other parent who is unreliable and selfish.