there are a lot of factors involved here. 1. you have never met this person and, until you do, will not know if there is actual sexual attraction. 2. your values are very different when it comes to sexual expression and fidelity.

considering the issues, i would not go beyond the status of "friend" right now. you have never gone out on a date. you do not know if you will click physically. there are a lot of differences and issues.

i am gay. i have been hit on by male to female trans people. but, i am not attracted to females and found it confusing. i could not envision how my needs would be met in such a relationship. while this is different from your status, there are some similarities. maybe bisexual men would be a better option to investigate for your romantic needs?

in answer to your questions, casual sex before relationships is not considered cheating in the gay community. in fact, it's very common, especially if both parties have a love interest in mind. in the gay community, it is common to rush into things, especially if you are young. i am not supporting or recommending such behavior, i'm just saying that's the way it is. i once had a friend brag that he waited until the third date to sleep with his eventual partner, as if he "waited" and didn't rush! another friend thought that love was like a pair of pants - you try it on (by sleeping with someone) a couple of times before you really know if it's a fit (love). so, it's often sex first, love later. again, this is not my recommendation, it's just the way it usually is.

frankly, i don't see you in a romantic relationship with him currently - you have never held hands or kissed or laid eyes on each other. you are friends. my suggestion is that you try to meet someone locally. i know it's harder for you. with your values of falling in love before sex and fidelity to the relationship, it's better to first set a goal of making friends and then hooking up with one who shares mutual attraction and values. it's a slower process and difficult because of your social anxiety. but, it's the way to go. also, i suggest - as someone who also has relationship issues - that through this whole friend to lover process that you see a T to help you deal with social anxiety and BPD issues because they make matters complex. all the best to you!