Text Message Witness

Recently I received a text message from someone that I didn't know... well I didn't know the number. Thinking that maybe it was a friend of mine that had changed their number I responded, "Who is this?" Well turns out that it wasn't someone I knew at all... just a mistake (he thought he was texting someone else). Well, I felt like maybe this was an opportunity so I asked him if he had anything he wanted me to pray for. Well, to make a long story short it turns out that he had lost his job and is struggling in his faith. So I text with him for a while talking about God and faith and even invited him to my church. Well, he asked if we could be friends and I told him that I couldn't really be "friends" with someone that I had never met and that I wasn't going to meet him either (unless he came to my church) due to the fact that it wouldn't be appropriate. I told him though that I would continue to pray for him. I thought it would end there, but every day he would send me text, usually just something like "hi!" or something what he had just done "Just went on a run!" It was weird and most of the time they were things that there is really no response to... so I usually just ignored them. Yesterday he sent me a text saying he was going to a movie that Stephen and I had been thinking about going to so I asked him to let me know how it was. Well, today he kept sending me text but they were really nothing to respond to so... I didn't. Well, he then sent me a text angry at me for not responding and calling me a bad Christian, among other things. I then responded saying that I was sorry that he felt that way, but that I hadn't meant to be mean, I was just busy with my kids and really didn't know how to respond to his texts. I also reminded him that I had told him that I didn't think it appropriate for us to talk any more about anything other then God things. He then responded with an "F you!" I just responded by telling him I would continue to pray for him. What else was I suppose to do? Should I have not ever responded in the first place? Was I a fool to think that I could witness to someone through text messaging!?! I feel like I am! I was so excited by the fact that I could have an impact on someone I didn't know for Christ! Then it all turned into a mess! Now he probably wants nothing to with Christians. Is there a better way I could have gone about it? I am just so frustrated and angry with myself right now.