I've worked with a few ex-offenders over the years, sometimes under the top level of MAPPA. I always make sure I don't know any detail of their offences and never google them!
It's tough, but I deal with it by being ultra-professional. Never engaging in personal conversation, or giving away personal info (I'd just say it would be against our procedures if asked a personal question), and almost putting a mental barrier between me and them, and constantly reminding myself that I must not judge them. They're entitled to the same level of support as any other client, and I say that to myself over and over again.
I have a massively supportive manager, who makes sure she is available after those visits if I need to offload, and that helps an awful lot. On one occasion, I had to raise a safeguarding because a client with a forensic history involving children got into a relationship with a single mum, who was herself vulnerable. My manager allocated another worker after that, in case he sussed that it was me and became ... difficult.
I'll be working with another one soon, grooming and child prostitution offences, and I'm not looking forward to it. But then I'd rather it was me than one of my colleagues who can't work in that sort of "semi-detached" way.
The thing that freaked me out the most was working with a man (not an ex-offender) for 6 months, doing home visits alone, and then seeing in the local paper that he'd been sentenced to 15 years for raping 2 women.
That made me feel really sick and very vulnerable, and I really lost confidence in my instincts for a while after that, because I never got that sort of vibe from him.