Sorry to hear about your situation. It doesn't sound like your friend is valuing your guys' friendship, at least not in the way you would like to be valued. I've been there, many times, and it's pretty sucky. Based on what you've said, it sounds like you're pretty clear on what you DON'T like in a friendship (i.e. friend not wishing you a happy birthday, not taking the time to reach out to you to hang out, etc.).
This is good, because from there you can get clear on what it IS that you want in your ideal friendship! No one's perfect and I don't think anyone ever matches up to our standards exactly 100% of the time, but as long as you have a clear set of criteria for the kinds of friends you do want in your life, then it'll make it that much easier to know whether or not you should even care about keeping someone in your life.
So, what does your ideal friendship look like? What would you guys be doing, what kinds of conversations would you be having, how do you feel when you're hanging out with your ideal friend? Write it out, sit down, close your eyes, and literally visualize an entire scenario.
Then comes the next step, which is to ask yourself, "Am I doing these things in my friendships or potential friendships?"
I'm not saying you're not, but it's easy to be hyperfocused on the wrongdoings of the other person (it's human nature) and blame them, but really think about whether or not you've been offering yourself in the way that you wish others would to you
If you've thought about it and have confirmed that, yes, this other person is not returning the love that I am giving (and I'm not just hoping and expecting them to do all the heavy lifting of the relationship--it takes two to tango), then you have two decisions to make. Actually three.
1) You can stay in the relationship, continuing to hope for a different result that you aren't going to get, unless the other person suddenly realizes their terrible lack of friendship etiquette and makes sudden changes that suit your liking
2) You can stay in the relationship and change YOUR OWN thinking. Meaning you become very flexible to this person's style of how they choose to be with you. You become okay with it and stop expecting the other person to change.
3) You can say, "Screw this person. I don't need this crap. I'm ****ing awesome and there are other people who WILL appreciate me, once I stop wasting my precious time and energy on this person." And then you start exploring spaces where like-minded people hang out and go from there.
You are awesome, and intelligent, AND you know you're deserving of better, more loving treatment. How do I know this? Because you're seeking help and advice on this forum, which means that there's a part of you that wants confirmation (and that your inner being already knows) that you are super cool and interesting. Otherwise you'd still be dicking around, feeling badly about yourself and NOT seeking the opinions and advice of other people. But you're not. You're here seeking to improve your life's situation, so that's an awesome first step to begin with. Know your worth, 'cause you've got it!
Hope this helped