You are in a position where you are being sexually harassed and if your interaction with him in the workplace is not very pleasant, then he is also probably creating a hostile work environment for you. If he does not stop soon, you will be in a position of asking your employer to help you end the harassment or you will have to go to the police -- I know that either choice is not pleasant -- but let me tell you what the law is regarding each of these situations and then I will give you some suggestions on how to approach the matter.
First, in order to have an actionable legal claim against your employer for sexual harassment and/or a hostile work environment, you must first formally report the issues to your employer and give the employer an opportunity to take care of the problem within the organization. By "formally" I mean an actual written complaint where the employer launches a full investigation -- they interview both parties, interview persons who might come in contact with the two of you and come to a decision on what to do in the matter, whether it is separating the two of you, or reprimanding him for harassing you and telling him that he will be terminated if it continues, up to a full termination of him if he persists. If you go to HR to informally report the behavior, the employer will probably never write it down and if in a lawsuit situation later, when you claim that you had informally reported it to HR (or supervisory personnel), they will all have lapses in memory and suddenly claim that they are not sure if you ever said anything to them, and the university defense will be "well, it was never formally reported to us, so how could we have done anything about it?". If this situation ever actually gets to a point where you are considering action against the employer, your first step would be to file a complaint with the Equal Employment Opportunity Commission (EEOC), which complaint must be filed within 6 months of the last "action" that happened to you at or with your employer (for example, if you were terminated because of this situation after reporting it) and go through their hearings process. If they find in your favor, they issue a "right to sue" letter which can be used in court as proof that you were being sexually harassed (at that point, most employers will generally settle the case).
Second, regarding any criminal legal action you may take, you can certainly involve the local police -- there are laws against making general threats against other people and if you have some of them on recorded calls, etc., it can be used as proof against him in court. Even if what he is doing does not rise to the level of stalking you, he can be charged with the threats and perhaps then he might stop this behavior. Another concern for you is that you really don't know if the threats might at some point rise to the stalking level -- and if you report it to the police now, and the situation escalates, at least the police will have some records of you making these complaints against him so that it doesn't look like you are coming out of the blue with stalking accusations.
Third, I suggest that you sit down at the computer and pull together a written timeline/journal of all incidents with this man. You should write down dates, times, what happened and what people were present when these things happened. Go back to about the end of the relationship and work your way forward by dates. If you keep it in sort of a "timeline" format, if this case ever does end up in civil or criminal court, such a document is generally admissible almost as your "notes" of what was happening at about that time period in your life and such a timeline/journal can be very powerful because everything that happened from your perspective will be viewed by the judge and jury, even if some of the people that you mention in it are not present in court (it gets you around the hearsay rule that you cannot testify to something that someone said if they are not in the court room to state it themselves). Also, try and get the transcripts of as many of these text messages if you can (if you cannot, then write the contents of the message in the journal with the date and time and where you were when you received the message) -- many cellphone companies now provide them on line as part of your account if you pay an additional fee. If you are unable to get online access to the messages, the phone company might not give them to you without a subpoena -- however, they might give them to the police if you grant your permission. Finally, Virginia is a "one party" consent state when it comes to recording of telephone or in person communications -- which means that pursuant to VA Code 19-2-62, you can record these conversations so long as one party is aware of and consents to the recording -- and that one party can be YOU. So, you need to record as many of these conversations as you can if you have not been doing so already. Save the voice messages as well -- they can be used in court because when a person speaks into an answering machine, they know full well that they are being recorded and they have no expectation of privacy in that message left on the machine.
What you want to do or decide to do in this situation is a decision that only you can make. I cannot tell you what to do -- only give you your options under the law. I can understand that you have fears of losing your job -- but, if there are no general rules against employees dating each other then perhaps you should report it to HR informally at first and ask them to speak with him to stop doing this to you and you might casually "drop" that you have been saving a "few" of the texts and calls in case his behavior gets worse and you have to go to the police. If the HR person you are speaking with has any sense, someone will sit him down and explain the problems he could be creating for the employer and perhaps he will stop once he is spoken to. Other than trying to handle this in an "informal" manner, my suggestions are above -- make it "formal" with the employer or go to the police (the police might even simply speak to him and let him know that making these threats is criminal behavior and he can be charged with a crime for his actions -- sometimes people do not realize that there is a general criminal charge for "threats" and once they are informed that they can be charged, they stop the behavior).
I hope that this helps. Please let me know if you have follow up questions.
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