Best friend passed away & his partner is disturbing me

I lost my best friend to cancer on April 20th, we had been close for 8 years practically inseparable until he began to see a new man 3 years ago. I had met up with them both a few times but always found his partner to be quite arrogant and bolshy but made the effort for my best friend. Upon losing my best friend suddenly after he returned from along haul flight and became very sick, his partner and I swapped number in case he needed my support with the funeral. I am also close with my best friend's family, inparticular his 2 older sisters, I helped them with some arrangements. On the day of the funeral my best friend's partner took centre stage, not allowing anyone else to stand and recollect any memories of the person we had lost, I could tell the 2 sisters were distraught by this. At the wake he continued to remain centre of attention, the sisters and family members attempted to make an announcement about donations to charity on behalf of my friend but he took over. In the weeks that followed I was bombarded with messages which concerned me - how he was hurting and I agreed, telling him some of my fond memories to try and help us both through. We then met up for the first ever time on our own, which was awkward to begin with, he told me he had been out clubbing until 5am and how a variety of men were desperate for him to take them home, this noticeably upset me, I am not judgemental at all but I just found it disrespectful to my friends memory. He then met my partner of 9 years and proceeded to drop in comments about his looks, which at first I laughed off as did my partner. We then parted and he continued to text me almost on an hourly basis - sometimes throughout the night. He called me and said he wanted my opinion of a house he was interested in renting, I went along and he proceeded to be crude in front of me and the current tenant, again - I am far from a prude but I was so embarrassed that I walked off. I went on holiday for a week and returned this friday, during my holiday he did not stop texting and trying to call, demanding to know what I was doing and also asking deeply personal and sexual questions about myself and my partner - i ignored all of these messages and turned my phone off each night only to wake up and switch it on to be bombarded with more messages - questions he would have known the answer to, asking me do I want my friend's art that was hanging in his flat, then telling me i need to reply and tell him when we get home... all kind of things that when you are away on your main summer holiday you don't really need to read. I told my partner about the sexual content of his messages and he told me to block his number, i have also spoken with my mum who said the same. My friend's sisters have previously advised me that they never trusted this man and put up with things for their brother's sake, he continually speaks about his own pain and grief and has not once asked myself or the sisters how they are, he has become demanding because i have not replied to any messages, telling me he needs an explanation... I just need some balanced advice from someone please, i feel stuck because he was my best friend's partner, i fell i am being guilt tripped into forging a friendship with a person i wouldn't normally have anything in common with whatsoever, i find him deeply rude and unpleasant, the sisters have since told me their brother would make arrangements to see me when his partner was away with work because he was so obnoxious in public... Please - any advice would be great, thank you.

I am really sorry for that ;-( ;-( Just stay away from that guy

Thank you for your condolences & advice :-)

I have said I need time to come to terms with his passing, my holiday was part of my plan to help with this but as mentioned he wouldn't leave me alone, even though I didn't reply to a single message I was still reading all about his grief and then his crude questions... And no - you are right I wouldn't usually put up with this behaviour from anyone in normal everyday life, I do feel I'm being lenient because of his relationship with my best friend, I hate have falling outs with anyone and it very rarely happens. I have suggested grief counselling as it's something I have had in the past and it did help - he said no because he "has too many secrets"... his behaviour is really dragging me down and yes - I need to stop it. Thank you for taking the time to respond.