How to reply to an ex-boyfriend's message?

Dear ex-boyfriend, thank you for your message, let me know that you still have nostalgia for our feelings. However, we have been apart for a long time, and life is getting farther and farther. Although I have been in love, I am now another person's girlfriend and I have started a new life myself. I know this sentence is cruel to you, but I want to tell you that I don't want to go back. Not wanting to look back is a decision, and our story is over.

Thank you and bless you.

Ex-boyfriend, we used to live together. Although we have no feelings for each other now, I still appreciate your company. Thank you for everything you have done for me, and I wish you can find the one who belongs to you and make your life more meaningful and better. We have come a long way, which is very important to us, but it is over now. We should all look forward and find our own happiness.

End with friendship

Ex-boyfriend, I think we have come to an end in the past story. But I hope we can end our relationship in a friendly way. We used to live together, and now we should try to understand each other in different ways and accept each other's status quo. If you need my help, I will lend a helping hand at any time, and let us walk through each other's lives in friendship.