QueSera,
I kind of go back and forth on a couple things about his amends... If he knows he is blocked and deliberately texted you from a different number, that's kind of creepy. But I'm not sure how you would feel about an actual paper letter, which seems kind of more respectful....
As for forgiveness... I'm having a hard time with that. I think that amends are about showing the people we have wronged that we are truly sorry for the wreckage of our past. As one person said, there is no boilerplate language. We have to say it our own way. I tend to believe though that it's really not our right to expect forgiveness. Forgiveness is lovely and welcomed, but it's a bonus really. It's about honestly atoning for our mistakes. What you do (or don't do) in response is entirely up to you.
One thing I'm sure of: you owe him nothing. Nothing at all. Respond if you like, but only if you want to.