WELL DONE! On getting rid - keep him rid! Block on everything and even consider getting a new mobile number and telling people you've a dodgy ex and not to give it out!
Op you are only a little older than my dd and I'm going to tell you something I have drummed into her!
Being single is perfectly acceptable option at ANY stage of your life.
No man/partner should ever make you feel bad about yourself. If they don't enrich your life and treat you KINDLY cut them loose.
Please please get some therapy so you don't find yourself in another similar relationship. Uni's have this kind of support available and believe me they deal with this type of situation ALL the time. It's sadly all too common.
This was an emotionally abusive relationship (and I suspect financially too I HOPE not physically or sexually) and it takes time to recover from that and reach a point you can enter a healthy equal relationship.
Give serious consideration to remaining single while at uni and focus on studies. You can still have plenty of fun without being in a relationship.
I have been single to all intents and purposes since I split with dds dad almost 20 years ago. I have dated at times but nothing really serious. It would take someone very very special to make me give up my independence and do a ton of compromising.
Dd has been single for the past year or two after breaking up with childhood sweetheart mainly due to career/uni options they decided on that weren't compatible but which they both wanted to pursue rightly so. They remain good friends BUT he always treated her well.
Previous boyfriend was a dick! Which caused some tension with us, was a relief when she saw his true colours. Unfortunately when they split he started stalking her! We got that sorted though.
Good men/partners do not treat people like this EVER.
Your sister is spot on!!