TL;DR A friend of mine moving overseas fell in love with me, I made it seem like I was also into it, started dating someone else, and slowly stopped talking to my friend.

Long wall of text incoming

Last year, I (27M) moved to a large metropolitan area, knowing virtually no one there. I got a job working on a team of eight, including a girl that I'll call Laura. Laura is cute, not really my type, but we have a lot in common including an affinity for our hometown sports team. We spend a lot of time together going to happy hours with coworkers, playing board games, generally being friends- certainly nothing romantic. 

Fast forward five months and we start chatting a bit more often, frequently about more and more intimate things. Because we work together, we still deny any feelings starting to develop. The next month, she finds out she's moving overseas. She quits her job, but before she quits, I do some pretty sizable farewell gestures, including planning a going away party. At this point, it's clear we definitely have feelings for one another and, because she's no longer part of our org, we start making out and eventually hook up a couple times. Because she's going overseas for a few years, we have a long discussion that I shouldn't wait for her and that if we start to date other people, it's ok.

Laura moves overseas to a place where she knows absolutely no one. She helps me apply for her job, which I get. We text NONSTOP. We send each other dirty pics, talk often on the phone, tell each other we love one another. She meets a few local people but still doesn't have all that many people. Meanwhile I'm continuing to make friends in the city I live in, meet new people, generally continue on with my life.

In August, about five months from when she left, I met this girl (Nicole) that I fell absolutely head over heels for. Because I was interested in cultivating this new relationship, I started to spend more time with Nicole and less time talking to Laura. I don't want to upset Laura with the development of a new relationship, so I don't tell her about Nicole, especially if it doesn't work out. Laura seems to notice something's off, and asks me about it- I tell her everything is fine. We continue to chat, though at a lighter rate; I read her texts and don't respond right away like I used to. In my mind, it now feels like I'm in two relationships.

I decide to tell Laura that I'm seeing Nicole to help explain why I'm being so distant. I text her (probably the bad move) and tell her that I'm seeing someone and want to talk to her about it. She says ok, we can talk on the phone after I'm out of work. After I get out of work, I give Laura a call. Laura is furious at me, saying I destroyed her trust, ruined our friendship, that I'm a pussy for not telling her about Nicole sooner. She says she no longer wants to talk to me until I think about the situation and apologize. I say ok and hang up.

In about a week, I send Laura a long email apologizing for hiding my relationship from her and being so distant. We talk for a while and she agrees to start talking to me again under one condition: If I start getting distant again, she's going to stop talking to me for good. I say ok and hang up.

Fast forward a few weeks and we're still chatting a bit but this time I notice her getting a bit more distant. Short answers, curt responses, no longer continuing conversations. I figure she no longer wants to talk and stop talking. She doesn't resume conversation. That was the last time I talked to her- she's now blocked me on all social media, blocked my number, and told other friends of ours about the situation, essentially turning those friends against me. 

On one hand, I understand why she's mad at me- I basically continued a relationship with her after she moved and didn't address the issue when something else came up. On the other hand, she chose to move away, understood I wouldn't wait to be in a relationship with her longterm, and didn't bring it up further when it seemed like I was pulling away. So the real question is- am I an asshole or is this just an unfortunate circumstance in which I lose a good friend of mine? Any advice would be great here.